SERPINE1 and melanoma: Since PAI-1 facilitates PD-L1 endocytosis of melanoma cells to abrogate the efficacy of anti-PD-L1 Abs in mouse melanoma models [91], and since baseline serum PAI-1 levels and PAI-1 expression on melanoma correlate significantly with the efficacy of anti-PD1 Abs for the treatment of advanced melanoma [92], blockade of the PAI-1 signal in combination with anti-PD1 Abs might enhance the anti-tumor immune responses against melanoma growth.