Furthermore, we previously revealed that PAI‐1 inhibition in fibroblasts was not associated with TGF‐β inducing Smad signalling pathway and non‐Smad signalling pathways, including ERKs.10 PAI‐1 was also shown to be involved in the apoptosis of cancer cells,18 endothelial cells, and neurons.31 From these observations, we conclude that apoptosis is an important mechanism by which PAI‐1 maintains the MF characteristics of CAFs. The gene discussed is TGFB1; the disease is cancer.