CD4 and cancer: To investigate the apoptotic landscape of malignant cells in ccRCC, we first performed unsupervised clustering and annotation of integrated single-cell RNA sequencing data, identifying major cell populations including cancer cells, endothelial cells, fibroblasts, monocytes, macrophages, cycling cells, CD4+ and CD8+T cells, NK cells, dendritic cells, B cells, plasma cells, mast cells, renal tubular epithelial cells, and collecting duct cells (Fig. 1A).