MITF and melanoma: Expression of MEL/MES genes in our melanoma cell lines revealed distinct patterns suggesting the culmination of multiple regulatory inputs, including graded (linear) relationships for canonical marker genes such as MITF (MEL) and ZEB1 and AXL (MES) or switch-like expression (abrupt and non-overlapping “on” or “off” levels of expression) for genes such as SOX10 and EDNRB (MEL) and EGFR (MES) (Fig. 3a).