KRAS and colorectal cancer: In non-small cell lung cancer, miR-21 increases K-ras-dependent (Kirsten-rat sarcoma viral oncogene homolog) tumor formation, whereas in colorectal cancer, expression of miR-21 was reported to be inversely correlated with expression of tumor suppressor gene PDCD4 (programmed cell death protein 4), and in PDAC modulates gemcitabine resistance and correlates with overall survival (OS) [27,28,29].