CD274 and ovarian carcinoma: When ovarian cancer cells were co-incubated with platelets for 24 h, EpCAM mRNA expression decreased (P = 0.0404) (Fig. 5b) while the mRNA expression of the immune checkpoint marker PD-L1 (CD274) increased (P = 0.0174) in cells cloaked with platelets (Fig. 5c).