(A) 451Lu and 451Lu-R cells were treated with increasing concentrations of 885. Cells lysates were analyzed by immunoblotting. (B) 451Lu and 451Lu-R cells were infected with either a control [C] lentiviral shRNA or 3 different clones targeting BRAF (1, 3 or 4). Cell lysates were analyzed by immunoblotting. (C) 451Lu-R cells were infected with lentiviral shRNA directed against CRAF or GFP. Infected cells were treated with 1 μM 885 (+) or left untreated (−) for 24h. Cell lysates were analyzed by immunoblotting with antibodies against CRAF, pERK, and total ERK (loading control). (D) 451Lu-R cells were infected with lentiviral shRNA against ARAF or GFP. Infected cells were treated with 1 μM 885 or DMSO for 24h. Cells were harvested, lysed and analyzed by immunoblotting with antibodies against ARAF, BRAF, CRAF, pERK, and total ERK (loading control). (E) 451Lu–R cells were sequentially infected with lentiviral shRNA directed against CRAF followed by ARAF. Infected and control cells were then treated with 1 μM 885 for 24h (+) or left untreated (−). Cell lysates were analyzed by immunoblotting. (F) After lentiviral infection, cells were treated with DMSO or 1 μM 885 for 72h. Cells were harvested, fixed, stained with propidium iodide and analyzed by flow cytometry. The percentage of cells in G0/G1 is indicated for each condition. See also Figure S2.