Indolocarbazole GO-6976 inhibited the calcium-dependent protein kinase C (PKC) isozymes alpha and beta 1. As PKC is a central enzyme that modulates numerous biological functions GO-6976 is extensively used as a tool for studying the involvement of PKC in signal transduction pathways. GO6976 was originally synthesized by Goedecke (formerly a subsidiary of Warner-Lambert, now Pfizer) in Germany. Preclinical investigations carried out by Goedecke have been for the potential treatment of HIV infections. Preclinical research with GO 6976 had been conducted by Biomol Inc. and Calbiochem in the USA as a potential treatment for cancer. No further information has been available for the compound therefore it is assumed that development has been discontinued. In addition to GO-6976 inhibition of PKC, it was reported that GO-6976 also inhibits JAK 2 and FLT3 tyrosine kinases and non-kinase transmembrane guanylyl cyclase.

PF-06439015 is a potent and selective inihibitor that overcomes clinical ALK (receptor tyrosine kinase anaplastic lymphoma kinase) mutations resistant to Crizotinib. PF-06439015 is potent across a broad panel of ALK mutant cell lines with an IC50 of 6.6 nM for tumor growth inhibition in a crizotinib-resistant cell line (H3122-L1196M).