RAET1G (retinoic acid early transcript 1G) is an NKG2D ligand that activates natural killer cell immunity. RAET1G encodes a class I-like MHC-related glycoprotein with structural features distinct from other ULBP family members 1. The protein exists as two isoforms: a full-length transmembrane form (RAET1G1) primarily retained intracellularly, and a truncated soluble form (RAET1G2) that can be secreted 2. RAET1G binds weakly to the NKG2D receptor compared to related ULBP2, with differential binding determined by a single amino acid substitution in the alpha2 domain 3. This reduced avidity results in less efficient NKG2D downregulation and NK cell degranulation 3. RAET1G is broadly expressed across tissues but shows particularly elevated expression in epithelial cancers and inflammatory conditions like celiac disease 2. Post-translational modification can generate a GPI-anchored isoform at the cell surface 4. Clinically, RAET1G expression exhibits opposing prognostic significance: in cervical cancer, elevated RAET1G expression correlates with shorter disease-free survival 5. RAET1G exists with population-specific polymorphisms that show linkage disequilibrium with other RAET1 genes 67. As an NKG2D ligand, RAET1G participates in immune surveillance of stressed, transformed, and pathogen-infected cells 8.