Cooperation of vitamin D receptor and retinoid X receptor ligands on differentiation of colon carcinoma cells. (A) E-cadherin levels in SW480-ADH cells treated with the VDR ligands in the presence and absence of 1 μM 9-cis-RA. The membrane was reprobed with an anti-lamin antibody. (B) After the same treatments, differentiation was tested by immunofluorescence with E-cadherin. Scale bar, 100 μm. 9-cis-RA, 9-cis-retinoic acid. RXR, retinoid X receptor; VDR, vitamin D receptor.