VSIR and myeloid sarcoma: Further functional evaluations of microglial VISTA in MS lesions revealed that VISTA has a differential expression in various stages of MS lesions, with the lowest expression during inflammation, and its knockout can stimulate morphological and transcriptional alterations toward an immune-activated and proliferative profile with amoeboid morphology and overexpression of genes involved in TNF and IFN signaling as well as the cell cycle.