IGBP1 (immunoglobulin binding protein 1) is an X-linked phosphoprotein associated with the B cell receptor complex that plays multiple roles in signal transduction and protein regulation 1. The protein is structurally related to yeast TAP42, a component of the rapamycin-sensitive signaling pathway 2, and regulates phosphatase activity by protecting partially folded catalytic subunits of PP2A, PP4, and PP6 from degradation until association with regulatory subunits. IGBP1 influences B cell differentiation, proliferation, apoptosis, and tolerance 1. Clinically, IGBP1 serves as a biomarker for lupus nephritis (LN) activity. Serum IGBP1 levels >547.45 ng/mL show 93.8% sensitivity and 96.9% specificity for detecting active renal disease 3, correlating with proteinuria and renal disease activity indices 1. Elevated plasma IGBP1 predicts future LN development in SLE patients without nephritis 4. IGBP1 expression is enriched in heart failure patients treated with SGLT2 inhibitors, supporting autophagy and mitochondrial health 5. An IGBP1 lncRNA variant (IGBP1-AS1) promotes nasopharyngeal carcinoma progression via miR-150-5p regulation 6. Mutations in IGBP1 associate with X-linked intellectual developmental disorder 7, though further validation is warranted.