Vitamin A mainly functions in MS by regulating the Th17/Treg cell axis through the active metabolite ATRA: ATRA binds to the nuclear receptor RARα, inhibits the expression of the key transcription factor RORγt in Th17 cells, reduces the secretion of pro‐inflammatory factors such as IL‐17 and IL‐23, and simultaneously induces the expression of the Treg cell‐specific transcription factor FoxP3 through the Smad3 pathway, promoting the release of anti‐inflammatory factors such as IL‐10 and TGF‐β (Elias et al. 2008). Here, RARA is linked to myeloid sarcoma.