SHMT1 and neoplasm: To further validate our conclusions, we used the ESTIMATE algorithm to assess the immune microenvironment of anti-PD1-treated patients and found that the expression of PSPH and SHMT1/2 was negatively correlated with patient immune scores (Fig. 7G to I), while PSAT1, PSPH, and SHMT2 were positively correlated with tumor purity (Fig. 7J to L).