MAP2K1 and melanoma: We first examined the cytotoxic effect of LT in four cancer cell lines with known mutations in the signaling axis of RAS-RAF-MEK1/2: murine melanoma B16-BL6, human colorectal cancer HT-29, and human melanoma MDA-MB-435 (MDA) [19] and SK-MEL-5 (SK-MEL) cell lines [6,20,21,22,23].