STK11 and melanoma: To investigate the role of LKB1 loss in migration and invasion of melanoma cell lines, LKB1 was knocked down in MeWo human melanoma cells (BRAF wild type) by small interfering RNA targeting on LKB1 (siLKB1), and non-specific siRNA (siCtrl), which has no target in human transcriptome, was used as a negative control.