DNMT1 and systemic lupus erythematosus: Certain studies have reported that the drugs commonly used to treat lupus do not inhibit DNA methylation (44,45); changes in the methylation status of SLE patients are unlikely to be the result of corticosteroid treatment (44,46) and the mRNA expression levels of DNMT1, DNMT3a, DNMT3b, MBD2 and MBD4 are not affected (43,44).