The cells were then treated with AZD6244 and AZ628 alone or in combination and cell proliferation was assessed after 96 hours (Fig. 5B). In the control LacZ or shLuc cells, AZD6244 and AZ628 potently inhibited proliferation alone and in combination. In contrast, expression of KRASG12V or knockdown of NF1 conferred resistance to single-agent treatment but retained sensitivity to the combination of both drugs...