A potent inhibitor of B-Raf (Kd = 0.3 nM) that less effectively inhibits c-Raf (Ki = 1.72 nM) and has little effect at 46 other kinases; blocks activation of ERK1/2 and anchorage-independent cell proliferation of melanoma cells with either wild type or V600E B-Raf at nanomolar concentrations.