To determine the in vivo antitumor efficacy of selumetinib combined with KRT-232, we evaluated five different CRC PDX models (C1035, B1011, C1185, C1114, and MDA-PDX.004 (PDX.004)) with different MAPK molecular characteristics (three KRAS, one BRAF, and one NRAS mutations). The gene discussed is NRAS; the disease is colorectal carcinoma.