PLK1 and melanoma: According to this study, the targets in expressing their cytostatic and cytotoxic action against melanoma, are: Adenosine A2a (the antagonist plays an important role in inhibiting promoter effect in melanoma tumor tissue); inhibition of glycogen synthase kinase (GSK)-3β, linked to the reduction of melanoma invasiveness; and inhibition of the Polo-like kinase 1 (PLK1), that the expression is dynamically regulated during the cell cycle in melanoma cells [9].