FOS and myeloid sarcoma: Of note, immediate-early genes (FOS, FOSL2, JUN, and JUNB) were found as DEGs in RRMS astrocytes over SPMS astrocytes (Figure 4C), which supported the previous identification of immediate early astrocytes (ieAstrocytes) that were identified in studies of EAE (an animal model of MS), and which increased in prevalence with disease severity (Groves et al., 2018).