What controls melanogenesis?

The pigments eumelanin and pheomelanin are the visually most striking products of specialized neural crest-derived cells (melanocytes), and provide color to both epidermis and hair shafts. While the intriguing and controversial biological functions of these multifaceted heteropolymers will be discussed in a later feature, here it is explored how their generation (melanogenesis) is controlled. For decades, this has been the object of much controversy, the salient features of which are delineated in the following contributions.