CD4 and breast cancer: We found that CASP9 expression is significantly positively related to the infiltration levels of CD8+ T cells (r = 0.126, P=7.61e − 05), CD4+ T cells (r = 0.13, P=5.45e − 05), macrophages (r = 0.073, P=2.22e − 02), neutrophils (r = 0.084, P=9.73e − 03), and dendritic cells (r = 0.023, P=4.84e − 01) (Figure 6), indicating that CASP9 promotes immune infiltration in breast cancer.