Fig. 1. Expression of CRB3 in mammary epithelial cell lines. (A) Immunoprecipitation of CRB3 from various epithelial cell lines. 1 mg protein lysate from each cell line was immunoprecipitated overnight with purified CRB3 antibody. Immunoprecipitates (IPs) were washed, resolved by Nu-PAGE gel electrophoresis as described in Material and Methods, transferred to nitrocellulose membranes and blotted with the purified CRB3 antibody. 2% lysate inputs are also shown. Positions of molecular weight markers (in kDa) are indicated on the left. (B) Tight junctions are poorly formed in MCF10A cells. MCF10A and MCF-7 cells were grown until 4 days post confluent on permeable Transwell filters as described in Materials and Methods. Cells on filters were fixed with 4% paraformaldehyde and stained for the tight junction marker ZO-1.