13-cis-4-Oxoretinoic acid 4-Oxo-13-cis retinoic acid 4-Oxo-13-cis-retinoic acid 4-Oxo-isotretinoin 71748-58-8 Oxoretinoic acid Retinoic acid, 4-oxo-, 13-cis- Ro 22-6595