CTLA4 and breast cancer: As shown in Figure 9, P2RX1 expression was significantly positively correlated with PDCD1 (r = 0.507, p = 3.84e-66), CTLA4 (r = 0.455, p = 6.07e-52) and CD274 (r = 0.351, p = 3.26e-30) in BC after adjusted by tumor purity.