BI-D1870

BI-D1870 is a specific inhibitor of the p90 RSK (ribosomal S6 kinase) isoforms, which inhibits RSK1, RSK2, RSK3 and RSK4 in-vitro. BI-D1870 does not significantly inhibit ten other AGC kinase members and over 40 other protein kinases tested at 100-fold higher concentrations. BI-D1870 does not affect the agonist-triggered phosphorylation of substrates for six other AGC kinases. Additionally, BI-D1870 does not suppress the phorbol ester- or EGF-induced phosphorylation of CREB (cAMP-response-element-binding protein). BI-D1870 induces apoptosis, although preferentially, in a p21-deficient background. BI-D1870 also induces a strong transcription and p53-independent accumulation of p21 protein and protects cells from gamma irradiation-induced apoptosis, driving them into senescence even in the absence of gamma irradiation.