Alternative definition : KEGG: Cutaneous melanin pigment plays a critical role in camouflage, mimicry, social
communication, and protection against harmful effects of solar radiation. Melanogenesis
is under complex regulatory control by multiple agents. The most important positive
regulator of melanogenesis is the MC1 receptor with its ligands melanocortic peptides.
MC1R activates the cyclic AMP (cAMP) response-element binding protein (CREB). Increased
expression of MITF and its activation by phosphorylation (P) stimulate the transcription
of tyrosinase (TYR), tyrosinase-related protein 1 (TYRP1), and dopachrome tautomerase
(DCT), which produce melanin. Melanin synthesis takes place within specialized intracellular
organelles named melanosomes. Melanin-containing melanosomes then move from the perinuclear
region to the dendrite tips and are transferred to keratinocytes by a still not well-characterized
mechanism.;