FIGURE 7.

Cell surface accessibilities of integrins α5, α6, and β1 were reduced by the expression of Muc21 with 84 TR. A, cells transiently transfected with mock, Muc21-4TR-IRES2-Venus, or Muc21-84TR-IRES2-Venus vectors were stained with anti-integrin α3, α5, α6, αV, or β1 antibodies, biotinylated second antibodies, and allophycocyanin-conjugated streptavidin and analyzed by flow cytometry. B, the adherent cells after transfection with mock or the Muc21-4TR-IRES2-Venus vector or the floating cells after transfection with the Muc21-84TR-IRES2-Venus vector were collected and lysed in lysis buffer. Cell lysates were separated electrophoretically on 7.5% polyacrylamide gels in the presence of 0.1% SDS and blotted onto polyvinylidene difluoride membranes. The blotted membranes were stained with anti-integrin α3, α5, α6, αV, or β1 antibodies or anti-β-tubulin antibodies. Although integrin subunits α3 and αV were below the control levels shown by the dots by flow cytometry, immunoprecipitates by the corresponding antibodies were observed by the Western blotting (WB).