GHR and melanoma: Therefore, in order to verify if PRL receptor (PRLR) activation affects MITF or MITF target gene expression, we analyzed the level of GHR and PRLR expression in all four human cell lines and observed that in RT-qPCR, the GHR Ct values were significantly higher than PRLR Ct values, reflecting a 10–30-fold higher expression of GHR compared to PRLR in these melanoma cell lines (supplementary Figure S11), similar to earlier reports [20].