Moreover, we observed that both the SFRP1 and SFRP2 transcripts are significantly negatively correlated with tumor purity and positively correlated with CAF infiltration in bladder urothelial carcinoma, but the SFRP2 gene showed a more distinguished correlation (Supplementary Figure 2 and Figure 2C). Here, SFRP2 is linked to bladder transitional cell carcinoma.