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Fig. 1. Expression and localization of InsP3R-3 during the polarization
of MDCK cells. MDCK cells, plated at 104 cells/cm2 were
cultured over a period of 12 days. (A) Western blot: 50 µg of protein of
cell lysates, corresponding to 1.2-1.4x105 cells from
cultures of 3, 6 and 10 days, were loaded on each lane; the last lane was
loaded, as a positive control, with a sample of HeLa cell lysate. Proteins
were subjected to 5% (w/v) SDS-PAGE and the western blotting was carried out
using a primary antibody directed against the type 3 InsP3R. (B)
TER. (C) Localization of InsP3R-3 and proteins of the endoplasmic
reticulum (ER) in MDCK cells cultured for 3, 6 and 10 days; in each case the
corresponding phase contrast images are shown on the left. (D) Localization of
another marker of the endoplasmic reticulum, the protein PDI, in cultures of 3
and 10 days, with the corresponding phase contrast image on the left. Bar, 10
µm.