In this study, to assess the expression level of MCM4 in pan-cancer, we used the TCGA database and the GTEx database and found that it was significantly upregulated in 24 cancers, including BLCA, BRCA, CESC, CHOL, COAD, DLBC, ESCA, GBM, HNSC, LGG, LIHC, LUAD, LUSC, OV, PAAD, PRAD, READ, SKCM, STAD, TGCT, THCA, THYM, UCEC, and UCS, and downwards in LAML, KIRC, and KIRP. Here, MCM4 is linked to cancer.