RARB (retinoic acid receptor beta) is a ligand-regulated nuclear receptor that functions as a transcriptional regulator of retinoic acid-mediated biological processes 1. As a heterodimer with RXR, RARB binds to retinoic acid response elements (RARE) containing tandem AGGTCA sequences to regulate gene expression 2. RARB acts primarily as a transcriptional activator due to weak corepressor binding and can function as both activator and repressor depending on target element context 3. Mechanistically, RARB regulates critical developmental and homeostatic processes. During prefrontal cortex development, RARB signaling controls regional patterning, thalamocortical connectivity, and dendritic spinogenesis through coordination with CYP26B1-dependent retinoic acid catabolism 2. In neuropathic pain, RARB maintains extracellular matrix homeostasis by transcriptionally regulating LAMB1, thereby modulating synaptic plasticity and associated anxiodepression 3. During ocular development, RARB regulates downstream targets like FOXC1 to control cell proliferation and differentiation 1. Clinically, RARB loss-of-function variants cause microphthalmia with developmental delay, while gain-of-function variants alter proper RARB regulation 1. RARB antagonism inhibits osteosarcoma proliferation through mTOR pathway regulation 4. In prostate cancer, RARB functions as a tumor suppressor frequently silenced through DNA methylation and polycomb repression 5. RARB also modulates susceptibility to prion diseases 6.