MITF and melanoma: Furthermore, although exogenous MITF causes a p21CIP1‐dependent cell cycle arrest in mouse fibroblasts and is a bona fide MITF target gene in melanoma cells (Carreira et al., 2005), cAMP – despite upregulating MITF – does not provoke an increase in p21CIP1 expression in melanoma cells (Wellbrock and Marais, 2005).