fig2

Figure 2. 3D molecular structures, molecular formula and molecular weight of 9-cisRA, 13-ciRA, ATRA, 4-HPR, and 4-Oxo-4-HPR (a metabolite of 4-HPR) molecules. Images were adapted from PubChem® (Available from: https://pubchem.ncbi.nlm.nih.gov/), National Library of Medicine, NIH.