CCN2 and cancer: As a transcriptional coactivator, YAP enhances the expression of connective tissue growth factor (CTGF),[29, 30] which subsequently activates cancer‐associated fibroblasts (CAFs) and induces collagen secretion.[31, 32] We observed significant upregulation of CTGF expression upon polycystin‐1 R3039H overexpression (Figure 7c; Figure S7c, Supporting Information), and exogenous CTGF treatment further elevated collagen I levels (Figure S7d, Supporting Information).