(A-C) (Left) RARα, RARβ, or RARγ knockdown in 2H11 cells by shRNA (qRT-PCR and western blot). (Right) RAR knockdowns on BMP4-stimulated osteocalcin expression (qRT-PCR). (D) RAR knockdowns on BMP4-stimulated nuclear pSmad1 at 48 h. (E-G) ATRA or 13-cis-RA on BMP4-stimulated osterix and osteocalcin expression (E), mineralization measured by Alizarin Red (F), or von Kossa (G) staining. (H) pSmad1 levels BMP4-stimulated 2H11 cells treated with Palo, ATRA or 13-cis-RA at 48 h. Histone H3, nuclear protein loading control. All samples were run on the same gel.