CD4 and cancer: Subsequently, we counted that DDR1 was significantly associated with the tumor purity in 22 types and subtypes of cancer in total and correlated with B-cell infiltration in 12 types and subtypes of cancer, CD8+ T-cell infiltration in 13 types and subtypes of cancer, CD4+ T-cell infiltration in 17 types and subtypes of cancer, macrophage infiltration in 18 types and subtypes of cancer, neutrophil infiltration in 17 types and subtypes of cancer, and dendritic cell (DC) infiltration in 15 types and subtypes of cancer, respectively (p < 0.05) (Supplementary Table S2).