Effect of vemurafenib on skin lesions and bone marrow. Skin lesions at start of therapy with vemurafenib (A) and after 10 months of treatment with vemurafenib (B). Bone marrow biopsy stained with an antibody against CD1a before (C) and after 9 months (D) of treatment with vemurafenib. Expression of the mutated BRAF protein in the bone marrow before (E) and after 9 months (F) of treatment with vemurafenib. Original magnifications ×20 (C-D) and ×40 (E-F).