A metabolite of all-trans retinoic acid; formed through metabolism of all-trans retinoic acid by CYP26A1, B1, and C1; binds to RARs with a lower affinity than other all-trans retinoic acid metabolites (IC50s = 606, 298, and 892 nM for RARα, RARβ, and RARγ, respectively, in a radioligand binding assay); transactivates RARs with a lower efficacy than other metabolites (EC50s = 791, 64, and 94 nM for RARα, RARβ, and RARγ, respectively) but induces transcription of a reporter plasmid equipotently; inhibits cell growth, halts the cell cycle in the G1 phase, and induces differentiation of NB4 acute promyelocytic leukemia cells (EC50 = 79.8 nM)