Paired sample analysis demonstrated low FCN1 expression in multiple tumor samples, such as bladder urothelial carcinoma (BLCA), breast invasive carcinoma (BRCA), and colon adenocarcinoma (COAD), while it exhibited high expression in clear renal cell carcinoma (KIRC) (Supplementary Figure S1D). Here, FCN1 is linked to bladder transitional cell carcinoma.