Fig. 4
Concentration-response curve of all-trans retinoic acid metabolites. Y-axis shows relative luminescent units (RLU). The dashed line represents the average value of controls, the gray solid line signifies the average value of 10−5 M 20α-hydroxycholesterol (20α-OHC) and the black solid line that of 10−5 M all-trans retinoic acid (ATRA). Each point represents the mean of triplicate determinations, and vertical bars represent the S.E.M. 4OH-ATRA: 4-hydroxy ATRA; 4 K–ATRA: 4-keto ATRA; 5,6E–ATRA: 5,6-epoxy ATRA