ESR1 and systemic lupus erythematosus: Additional details about estrogen-induced modulation of cytokine production in SLE mediated by the estrogen receptor and of the various aspects of estrogen receptor signaling in this disease, estrogen receptor subtypes, their structure, and the mode of action of estrogens by gene activation and via extranuclear effects are outlined in a recent review by Kassi and Moutsatsou [22].