STAT3 and urinary bladder carcinoma: As expected, the expression of MTHFD2 correlated positively with the expression of PD‐L1 (r = 0.7434, p = 0.001), and phosphorylation of JAK1 (r = 0.7926, p < 0.001) and STAT3 (r = 0.8613, p < 0.001) in bladder cancer tissues (Figure S4b).