Thus, we hypothesized that the antiproliferative effects of several RSK inhibitors might be caused by off-target inhibition of other protein kinases, such as PLK1, a master regulator of cell division and candidate for targeted therapy with increased expression in melanoma (Strebhardt et al, 2000; Kneisel et al, 2002; Chiappa et al, 2022). Here, RPS6KA1 is linked to melanoma.