literature is reviewed on the mechanisms of differentiation in mammalian melanoma cells and normal melanocytes . 
 pigment cells are particularly useful for studies requiring the observation of differentiation in living cells , for example , studies of commitment . topics discussed include melanin synthesis and other markers of pigment cell differentiation ; stochastic models of differentiation and commitment ; the lability of early stages of differentiation ; extracellular factors affecting pigment cell differentiation , with implications for intracellular controls ; the role of proliferation and the cell cycle in differentiation , and the relative roles of changes in transcription , translation , and posttranslational processes.imagesfigure 1 .