FIGURE 1.

ATRA induces the formation of adherens junctions and the reorganization of tight junctions. A, SKBR3 cells were treated with vehicle (ethanol) or ATRA (1 μm) for 24 h. The Western blots illustrate the amounts of VE-cadherin, α- and β-catenin, RARα, and tubulin in the Triton X-100-soluble and -insoluble cell extracts. Tubulin serves as a loading control, whereas RARα degradation is associated with ligand-dependent activation of the receptor. B, SKBR3 cells were treated as in A for 48 h. Immunofluorescence analysis was performed for the adherens junction proteins VE-cadherin and β-catenin as well as for the tight junction proteins occludin and ZO-1. The results are representative of at least two independent experiments.