HGF is a polypeptide growth factor that can bind to the MET receptor expressed on melanocytes, with HGF stimulation leading to MITF-dependent Met message and protein induction . The MET proto-oncogene encodes for the hepatocyte growth factor (HGF) receptor, a plasma membrane tyrosine kinase that is involved in melanocyte growth and melanoma development. When the ligand binds to the receptor, MET processes autophosphorylation on tyrosine residues produce the docking site for PI3K to promote growth and differentiation of melanocytes, thereby influencing melanogenesis via activation of the cyclic adenosine monophosphate (cAMP) pathway . DKK-1 secreted by fibroblasts mostly exists in the palmoplantar skin compared with the nonpalmoplantar skin . DKK-1 has the ability to inhibit melanocyte growth via regulating the Wnt signaling pathway in which DKK-1 suppresses β-catenin accumulation and then decreases MITF activity, thereby influencing the functions of the melanocytes. In a previous study, Wonseon Choi et al. used the microarray analysis to indicate in dark skin, and NRG-1 was the highly expressed factor secreted by fibroblasts and increased skin pigmentation . NRG-1 mediates melanogenesis through the PI3K pathway, increasing melanocyte proliferation and survival and melanin production. CRH is regulated by UV or as a response to stress. CRH can bind to its receptors, CRH-R1 and CRH-R2, and then induce the POMC-derived hormones, including MSH and ACTH released to influence the skin phenotype system . ET-1 functions as a mitogenic factor for melanocytes and facilitates melanogenesis. ET-1 can bind to its endothelin receptors A (ETA) and activate the cAMP pathway that increases protein kinase C activation to stimulate MITF expression. Akira Hachiya et al. demonstrated the responses of SCF and ET-1 to UVB irradiation, in which SCF responded in the early stage and ET-1 in the later phase of UVB-induced melanin production .