Probable GTP-binding protein (By similarity). Functions in innate immunity and more specifically the inflammatory response as a regulator of the Toll-like receptor TLR2 and TLR4 signaling pathways (PubMed:20616063, PubMed:26599367). Negatively regulates the part of the TLR4 signaling pathway that leads to the activation of the transcription factor AP-1. By retaining the phosphatase complex PP2A into the cytoplasm, prevents the dephosphorylation of the AP-1 subunit JUN which is required for proper activation of the transcription factor (By similarity). Both inhibits and activates the TLR2-dependent signaling pathway (PubMed:26599367). Positively regulates the TLR2 signaling pathway to activate specifically the downstream p38 and JNK MAP kinases and promote the polarization of macrophages toward the pro-inflammatory M1 phenotype. It may also play a role in the regulation of inflammation induced by high glucose through the PKB/AKT signaling pathway. Also involved in erythrocyte differentiation through activation of the ERK1/ERK2 signaling pathway (By similarity). Interacts with RAF1. Interacts with HSPD1. Interacts with PPP2CA; retains PPP2CA into the cytoplasm and excludes it from the nucleus. Interacts with PPP2R2A; the interaction is direct. Interacts with PJA2. Up-regulated by lipopolysaccharides (LPS) (at protein level). Ubiquitinated. Ubiquitination by PJA2 does not lead MFHAS1 to proteasomal degradation but positively regulates its function in polarization of macrophages.