CD4 and neoplasm: The results indicated that as tumor purity increased, the SPHK1 expression levels were negatively correlated with B cells (r = −0.144, p = 1.45E-03) and positively correlated with CD4+ T cell (r = 0.132, p = 3.65E-03), neutrophil (r = 0.295, p = 3.89E-11), and dendritic cell (r = 0.186, p = 3.39E-05) infiltration levels in the TIMER database (Figure 12A).