Ligand-induced RARA transactivation and degradation can be uncoupled and control distinct biological effects. (A) Structures of RA, etretinate (Etre), acitretin (Aci) and NRX195183 (NRX). (B) Western blot analysis of RARA-transduced rars−/− MEFs after 6 h of treatment with RA, acitretin, or NRX at 1 µM. Actin demonstrates equal loading. (C) RA, acitretin, or NRX (1 µM), activate cyp26 and rarb gene expression in rars−/− MEFs stably reexpressing RARA, mean ± SD of three independent experiments. (D) Dose–response analysis of RA, acitretin, or NRX for the activation of RARE3-TK-Luc, a luciferase RA responsive reporter gene, in RARA-transduced rars−/− MEFs. Results are expressed as percentage of maximal activation, demonstrating similar affinities of the three retinoids. Means ± SD of 3 independent experiments. (E) Correlation between RA-, acitretin-, and NRX-triggered gene activation in rars−/− MEFs stably reexpressing RARA and treated for 8 h. Logarithmic scale. Analysis was restricted to genes induced more than twofold by RA or uncoupled retinoids in the transcriptomic arrays. Linear regression of the data is shown. Mean values of two independent experimental replicates. (F) Effect of RA, acitretin, or NRX on colony formation of RARA-transformed lineage-negative (Lin−) primary mouse hematopoietic progenitors after the first plating in methylcellulose (means ± SD of 3 independent experiments). (G) Effect of RA, acitretin, or NRX treatment on the cells described in F after 1 wk of methylcellulose culture (May–Grunwald Giemsa [MGG] staining, top; bar, 10 µm) or 24 h in liquid culture (FACS analysis, log10 fluorescence, bottom). Representative experiment of three independent ones.