U0126 is a highly selective inhibitor of both MEK1 and MEK2, a type of MAPK/ERK kinase. The inhibitory effects of U0126 on MEK and ERK activation have been confirmed repeatedly, and treatments with U0126 have been shown to inhibit proliferation and migration of cancer cells in vivo and in vitro. U0126 has been widely used as an inhibitor for the Ras/Raf/MEK/ERK signaling pathway. U0126 treatments lead to cancer cell death, which agrees with the well-known role of the Ras/Raf/MEK/ERK pathway in supporting cell survival. U0126 enhances apoptosis in human breast cancer MCF-7 cells, acute myeloid leukemia, and PC12 cells.

Staurosporine is an alkaloid isolated from the culture broth of Streptomyces staurosporesa. It exerts antimicrobial, hypotensive, and cytotoxic activity. The main biological activity of staurosporine is the inhibition of protein kinases through the prevention of ATP binding to the kinase. This is achieved through the stronger affinity of staurosporine to the ATP-binding site on the kinase. Staurosporine is a prototypical ATP-competitive kinase inhibitor in that it binds to many kinases with high affinity, though with little selectivity. It is a potent, cell permeable protein kinase C inhibitor with an IC50 of 0.7 nM. At higher concentration (1-20 nM), staurosporine also inhibits other kinases such as PKA, PKG, CAMKII and Myosin light chain kinase (MLCK). At 50-100 nM, it is a functional neurotrophin agonist, promoting neurite outgrowth in neuroblastoma, pheochromocytoma and brain primary neuronal cultures. At 0.2- 1 uM, staurosporine induces cell apoptosis. Staurosporine is also a potent GSK-3β inhibitor with a reported IC50 value of 15 nM. In research, staurosporine is used to induce apoptosis. It has been found that one way in which staurosporine induces apoptosis is by activating caspase-3. Staurosporine was discovered to have biological activities ranging from anti-fungal to anti-hypertensive. The interest in these activities resulted in a large investigative effort in chemistry and biology and the discovery of the potential for anti-cancer treatment. Staurosporine induces apoptosis by multiple pathways and that the inhibition of more than one kinase is responsible for its potent activity. Because the mechanism of action of staurosporine is distinct from traditional anticancer drugs, this may warrant further preclinical evaluations of the antitumor potential of new staurosporine derivatives either alone or in combination with death ligands or conventional chemotherapeutic drugs.

BI-847325 is a novel, ATP-competitive, orally available inhibitor of Aurora kinases and MEK. In in vitro studies, BI-847325 inhibited the activity of Xenopus laevis Aurora Kinase B with an IC50 of 3 nM; with IC50 values for human Aurora kinase A and Aurora kinase C being 25 and 15 nM, respectively. BI-847325 also inhibited human MEK1 and MEK2 with respective IC50 values of 25 and 4 nM. BI-847325 had been in phase I clinical trials by Boehringer Ingelheim for the treatment of solid tumours. However, there is no development reported for this study.

Selumetinib (AZD6244 or ARRY-142886) is a potent, selective, and ATP-uncompetitive inhibitor of Ras-Raf-mitogen-activated protein kinase kinase (MEK1/2). This inhibition can prevent ERK activation, disrupt downstream signal transduction, and inhibit cancer cell proliferation and survival. Selumetinib has shown tumour suppressive activity in multiple rodent models of human cancer including melanoma, pancreatic, colon, lung, and breast cancers. AstraZeneca is responsible for development and commercialization of selumetinib.

Cobimetinib is an orally active, potent and highly selective small molecule inhibiting mitogen-activated protein kinase kinase 1 (MAP2K1 or MEK1), and central components of the RAS/RAF/MEK/ERK signal transduction pathway. It has been approved in Switzerland and the US, in combination with vemurafenib for the treatment of patients with unresectable or metastatic BRAF V600 mutation-positive melanoma. Preclinical studies have demonstrated that Cobimetinib is effective in inhibiting the growth of tumor cells bearing a BRAF mutation, which has been found to be associated with many tumor types. A threonine-tyrosine kinase and a key component of the RAS/RAF/MEK/ERK signalling pathway that is frequently activated in human tumors, MEK1 is required for the transmission of growth-promoting signals from numerous receptor tyrosine kinases. Cobimetinib is used in combination with vemurafenib because the clinical benefit of a BRAF inhibitor is limited by intrinsic and acquired resistance. Reactivation of the MAPK pathway is a major contributor to treatment failure in BRAF-mutant melanomas, approximately ~80% of melanoma tumors becomes BRAF-inhibitor resistant due to reactivation of MAPK signalling. BRAF-inhibitor resistant tumor cells are sensitive to MEK inhibition, therefore cobimetinib and vemurafenib will result in dual inhibition of BRAF and its downstream target, MEK. Cobimetinib specifically binds to and inhibits the catalytic activity of MEK1, resulting in inhibition of extracellular signal-related kinase 2 (ERK2) phosphorylation and activation and decreased tumor cell proliferation. Cobimetinib and vemurafenib target two different kinases in the RAS/RAF/MEK/ERK pathway. Cobimetinib is used for the treatment of patients with unresectable or metastatic melanoma with a BRAF V600E or V600K mutation. Cobimetinib is used in combination with vemurafenib, a BRAF inhibitor. Cobimetinib is marketed under the trade name Cotellic.

Trametinib is a reversible and specific inhibitor of mitogen-activated protein kinase kinases MEK1 and MEK2 which are involved in a RAS/RAF/MEK/ERK signaling pathway and control cell growth, survival, and differentiation. By inhibiting MEK1 and MEK2 trametinib blocks dual phosphorylation of ERK1/2 and stops cell cycling. In addition, trametinib blocks BRAF pathway in the cells with BRAF V600E mutations. Trametinib (as a single agent and in combination with dabrafenib) is approved for the treatment of unresectable or metastatic melanoma with BRAF V600E or V600K mutations.

Staurosporine is an alkaloid isolated from the culture broth of Streptomyces staurosporesa. It exerts antimicrobial, hypotensive, and cytotoxic activity. The main biological activity of staurosporine is the inhibition of protein kinases through the prevention of ATP binding to the kinase. This is achieved through the stronger affinity of staurosporine to the ATP-binding site on the kinase. Staurosporine is a prototypical ATP-competitive kinase inhibitor in that it binds to many kinases with high affinity, though with little selectivity. It is a potent, cell permeable protein kinase C inhibitor with an IC50 of 0.7 nM. At higher concentration (1-20 nM), staurosporine also inhibits other kinases such as PKA, PKG, CAMKII and Myosin light chain kinase (MLCK). At 50-100 nM, it is a functional neurotrophin agonist, promoting neurite outgrowth in neuroblastoma, pheochromocytoma and brain primary neuronal cultures. At 0.2- 1 uM, staurosporine induces cell apoptosis. Staurosporine is also a potent GSK-3β inhibitor with a reported IC50 value of 15 nM. In research, staurosporine is used to induce apoptosis. It has been found that one way in which staurosporine induces apoptosis is by activating caspase-3. Staurosporine was discovered to have biological activities ranging from anti-fungal to anti-hypertensive. The interest in these activities resulted in a large investigative effort in chemistry and biology and the discovery of the potential for anti-cancer treatment. Staurosporine induces apoptosis by multiple pathways and that the inhibition of more than one kinase is responsible for its potent activity. Because the mechanism of action of staurosporine is distinct from traditional anticancer drugs, this may warrant further preclinical evaluations of the antitumor potential of new staurosporine derivatives either alone or in combination with death ligands or conventional chemotherapeutic drugs.