Phaeomelanin, meaning rufous-black, is characterized by the presence of sulfur-containing cysteine, and it appears reddish to yellowish as a result. Melanosomes containing eumelanin are eumelanosomes, while those containing phaeomelanin are phaeomelanosomes. Melanocyte-stimulating hormone (MSH) binds to the Melanocortin 1 receptor (MC1R) and commits melanocytes to the production of eumelanin.