Macrophage‐myofibroblast transition (MMT) is a newly discovered pathway for mass production of pro‐tumoral cancer‐associated fibroblasts (CAFs) in non‐small cell lung carcinoma (NSCLC) in a TGF‐β1/Smad3 dependent manner. The gene discussed is TGFB1; the disease is non-small cell lung carcinoma.