TGFB1 and Peritoneal Fibrosis: When RPMC and HMrSV5 were stimulated by TGF-β, the extracellular matrix was deposited, and both the activity of calpain and the expression of calpain9 were increased (Figures 1K–P), which suggests that calpain may be involved in the development of peritoneal dialysis-related peritoneal fibrosis in rats.