IGF1 and myeloid sarcoma: These regulatory populations secreted higher levels of IGF1 and activin A than those of pro‐inflammatory phenotypes and promoted oligodendrocyte differentiation.45 Yu et al94 also reported similar findings as when microglia was polarized to regulatory state by inducing homeobox gene msh‐like homeobox‐3 (Msx3), levels of activin A, and IGF1 mRNAs were increased and facilitated remyelination in mice MS models.