Therefore, TGF-β1 derived from stromal fibroblasts is a critical mediator of crosstalk between stromal fibroblasts and BLCA cells, which dominates stromal fibroblast-mediated EMT of BLCA cells via the FAP/VCAN axis to promote the invasion and metastasis of BLCA (Additional file 10G). Here, FAP is linked to bladder transitional cell carcinoma.