Sorafenib (BAY 43-9006) is biarylurea-based inhibitor of Raf1 (IC50, 6 nM) with additional activity against B-Raf, mVEGFR2, mPDGFRb (IC50, 22 nM, 15 nM, and 57 nM respectively), and related kinases. [1] In MDA-MB-231 breast cancer cells, sorafenib efficiently blocks activation of the MAPK pathway. Dose-dependent inhibition of basal MEK 1/2 and ERK 1/2 phosphorylation was observed at IC50s of 40 and 100 nM, respectively. [1]

In hepatocellular carcinoma cell lines, sorafenib inhibited cell proliferation in a dose-dependent manner with an IC50 of 6.3 uM in PLC/PRF/5 and 4.5 uM in HepG2 cells. [2] Flow cytometry studies indicated a decrease in G1 and increase of S phase after sorafenib treatment in HepG2 cells.