LEFTY1 gene encodes a secreted ligand of the TGF‐beta superfamily.49 Interestingly, inhibition of the Ras/Raf/Mek/Erk pathway dramatically enhances TGF‐mediated Lefty1 up‐regulation.50 Thus, the up‐regulation of LEFTY1 could be explained by the low levels of pErk in the hiPSCs‐SLE. This evidence concerns the gene LEFTY1 and systemic lupus erythematosus.