The potency of GDC-0879 for a panel of melanoma, colorectal, and non–small-cell lung cancer cell lines is shown in Fig. 2...Tumor cells with oncogenic mutations in either KRAS or NRAS showed limited dependence on BRAF activity and were frequently resistant to GDC-0879 treatment in vitro (EC50 > 7.5 μmol/L for 28 of 32 cell lines).