Mechanistically, after incubated with interferon α (IFN-α) which is increased in SLE, CpG of lymphoid enhancer-binding factor 1 (Lef-1) in B cells was methylated, and then MBD2 selectively bound to the CpG to inhibit the transcription and expression of Lef-1, which in turn inhibited the transcription and expression of Pten, and thus regulate PI3K-Akt-mTOR signaling then affects the pathogenic progression of SLE. Here, PTEN is linked to systemic lupus erythematosus.