The article presents the melanogenesis pathway and the role of cyclic adenosine 
monophosphate (cAMP) and microphthalmia transcription factor (MITF) in 
regulation of this process. Products of melanogenesis are eu- and/or 
pheomelanins synthesized in a multistage process of tyrosine oxidation and 
polymerization. The conversions require the presence of tyrosinase (TYR, key 
enzyme), tyrosine hydroxylase isoform I (THI) and tyrosinase related proteins 
(TRP1 and TRP2). Many types of signal molecules and transcription factors 
participate in regulation of melanin synthesis, but the most important are cAMP 
and MITF. cAMP is the second messenger in the intracellular signal cascade, 
which is synthesized from adenosine triphosphate (ATP) by adenylyl cyclase, 
activated among others by the melanocortin receptor and the αS subunit of G 
protein. The signal molecule cAMP regulates MITF, TYR, THI, GTP-cyclohydroxylase 
I (GTP-CHI) transcription and phenylalanine hydroxylase (PAH) phosphorylation at 
Ser16 by protein kinase A (PKA). Mutations of genes encoding proteins belonging 
to the cAMP signal cascade may lead to McCune-Albright and Carney syndromes. 
MITF is one of the most important nuclear transcription factors regulating 
melanogenesis. Currently 10 isoforms of human MITF are known, but in melanocytes 
only MITF-M, MITF-Mdel, MITF-A and MITF-H occur. MITF transcription factor 
regulates melanogenesis by activation of tyrosinase, TRP1 and TRP2 
transcription. It also affects expression of other factors regulating melanosome 
maturation, biogenesis and transport. Moreover, it regulates melanocyte 
proliferation and protection against apoptosis. Mutations of the MITF gene may 
lead to hereditary diseases: Waardenburg type II and Tietz syndromes.