ABCG2 and cancer: Additionally, proteomic analysis across BRCA, COAD, and LUAD confirmed that nine hub genes (e.g., ABCG2, CAV1, CRYAB, DES) were consistently downregulated at both transcript and protein levels, consistent with the loss of their tumor-suppressive functions in cancer [117], [118], [119], while RRM2 was upregulated, consistent with an oncogenic function.