MERTK and systemic lupus erythematosus: These data are consistent with previous in vivo data showing circulating soluble ectodomains of Mertk [39] and that the elevated levels of soluble Mertk that are noted in vivo undergo pathophysiological conditions that include systemic lupus erythematosus (SLE) [15,50], atherosclerosis [51], SLE-induced kidney disease [52], an acute inflammatory response [36], and a COVID-19 cytokine storm [53].