KRAS and non-small cell lung carcinoma: Non-small-cell lung cancer (NSCLC) with Kirsten rat sarcoma (KRAS) mutations has notoriously challenged oncologists and researchers for three notable reasons: (1) the historical assumption that KRAS is “undruggable”, (2) the disease heterogeneity and (3) the shaping of the tumor microenvironment by KRAS downstream effector functions.