AP‐1 family members FOS and JUN regulate the malignant phenotype conversion of normal fibroblasts (NFs) to normal‐like cancer‐associated fibroblasts (nCAFs), while transforming growth factor‐β (TGFβ) and interferon‐γ (IFNγ) signals triggers the interconversion between classic myofibroblastic CAFs (myCAFs) and inflammatory CAFs (iCAFs), respectively. The gene discussed is FOS; the disease is cancer.