MC1R and melanoma: Overall, these data showed that (i) MGRN1-deprived melanocytes and melanoma cells were more pigmented than their corresponding controls, (ii) this stimulation of pigmentation was cell-autonomous as it occurred in the absence of keratinocyte-secreted factors or exogenous MC1R agonists and (iii) hyperpigmentation likely resulted from both an increased number of melanosomes and a higher percentage of melanosomes in highly pigmented stages III and IV, indicative of a higher rate of melanogenesis.