5,6-Epoxyretinoic acid
all-trans-5,6-epoxy Retinoic acid (5,6-epoxy RA) is an agonist of all isoforms of the retinoic acid receptor (RAR; EC50s=77, 35, and 4 nM for RARα, RARβ, and RARγ, respectively). 5,6-epoxy RA (1 μM) also induces growth arrest of MCF-7 and NB4 cells in vitro. It is a natural metabolite of all-trans retinoic acid, which is a metabolite of vitamin A.