CD274 and ovarian cancer: One study revealed that in ovarian cancer, STAT3-activated TAMs can express PD-L1 and bind to programmed cell death protein 1 (PD-1) receptors on T cells, leading to T-cell inactivation.72 The activation of STAT5 can promote the expression of various genes, including Bcl-xL and Mcl-1, which are related to cell survival and proliferation.