p16Ink4a and p21 are the main senescence hallmarks, the results of quantitative real‐time PCR and western blot showed that mouse in BLM group exhibited upregulation of p16Ink4a and p21 expression in lung compared with control, FOXO4‐DRI significantly downregulated p16Ink4a and p21 expression in the lung of mice with BLM‐induced PF (Figure S1E–G). Here, FOXO4 is linked to pemphigus foliaceus.