KRAS and colorectal carcinoma: Inherent resistance is also seen in patients with CRC whose tumors carry BRAF V600E (159), MAP2K1 (74) or PIK3CA (160) mutations, KRAS (161), ERBB2, MET or FGFR1 amplification (74), biallelic NF1 loss or aberrations in the non-canonical RAS/RAF pathway (111).