RASGRP4 functions as a mast cell-restricted, cation- and diacylglycerol-dependent guanine nucleotide exchange factor that activates Ras proteins by catalyzing GDP-to-GTP exchange 12. The protein operates downstream of the c-Kit receptor and plays crucial roles in mast cell development and function, with defective variants identified in asthma, mastocytosis, and mast cell leukemia patients 1. RASGRP4 regulates the expression of prostaglandin D2 synthase, controlling inflammatory mediator production in mast cells 2. Beyond mast cells, RASGRP4 significantly contributes to inflammatory and immune responses across multiple disease contexts. In diabetic kidney disease, RASGRP4 promotes inflammatory injury by facilitating interactions between peripheral blood mononuclear cells and glomerular endothelial cells, activating NLRP3 inflammasome and MAPK/NF-κB signaling pathways 3. It also exacerbates diabetic ischemia-reperfusion injury by mediating communication between macrophages and T cells through IL-17 signaling 4. In diabetic kidney fibrosis, RASGRP4 acts through Aloxe3-mediated oxidative stress to activate scar-associated macrophages 5. Additionally, RASGRP4 promotes M2 macrophage polarization in ovarian cancer via mTOR-STAT3 signaling 6, and its methylation status serves as a biomarker for tuberculosis disease progression and outcomes 7.