The most pronounced associations were observed in cervical squamous cell carcinoma (CESC), bladder cancer (BLCA), breast cancer (BRCA), and gastric adenocarcinoma (STAD), as depicted in Figure 4B. Specifically, in CESC (r = −0.44, p = 0), BLCA (r = −0.41, p = 0), BRCA (r = −0.31, p = 5.2 × 10−17), and STAD (r = −0.37, p = 3.9 × 10−13), BAP31 methylation exhibited a negative correlation with BAP31 mRNA expression, as illustrated in Figure 4C–F. This evidence concerns the gene BCAP31 and bladder transitional cell carcinoma.