Exosomal circPRMT5 is secreted into the tumor microenvironment and regulates the SNAIL1/E-cadherin signaling pathway by competing with miR30c, up-regulating SNAIL1 and inhibiting E-cadherin; thereby promoting the EMT of urothelial carcinoma of the bladder (UCB) cells, affecting the tumor microenvironment, and facilitating tumor metastasis 5 (Figure 2B). This evidence concerns the gene SNAI1 and urothelial carcinoma.