PF-04880594 is a selective inhibitor of B-Raf, B-RafV599E and c-Raf with IC50 value of 0.19 nM, 0.13 nM and 0.39 nM, respectively . Raf is a serine/threonine protein kinase and plays an important role in the MAPK/ERK signaling pathway. It has been revealed that Raf involves in cancers and developmental syndromes and its inhibitors are regarded as a promising target for cancer treatment . PF-04880594 is a potent Raf inhibitor. When tested with GTL16 and GTL16 resistant cell clones, PF-04880594 treatment significantly decreased cell viability and ERK activity . In 3D culture model of RHE cells (histologic similar to human epidermal lasers), PF-04880594 treatment (62.5 nmol/L, 2 d) significantly induced necrosis with ghost cells accounting for nearly 50% to 60% of the culture thickness via inducing p-ERK expression level . Treated nude mice model with PF-04880594 (10-40 mg/kg, twice daily for 3 weeks) and then mice were sacrificed for further study. The results revealed that PF-04880594 treatment induced ERK phosphorylation and B-Raf-c-Raf dimerization in multiple epithelial tissues which phenomenon could be attenuated by PD-0325901 .