Figure 1.

β-Catenin and plakoglobin, but not α-catenin, are cleaved during HUVEC apoptosis. (a) HUVEC were deprived of growth factors for 12–16 h, and apoptotic cells (A) which appear as “floaters” were harvested by centrifugation of the medium. The remaining adherent and viable cell population (V) and control cells (C) cultured in full growth medium were harvested with a cell scraper and centrifuged before cell lysis. Cell lysates (25 μg) were analyzed by separation on a 7.5% SDS-PAGE, by transfer to Immobilon membrane, and by Western blotting with monoclonal antibodies to α-catenin, β-catenin, and plakoglobin (γ-catenin). (b and c) HUVEC were deprived of growth factors for 0, 2, 4, 8, and 12 h, and floaters and viable cells were pooled, lysed, and analyzed by SDS-PAGE and Western blotting with monoclonal antibodies to β-catenin (b) and plakoglobin (c). A lysate of pure apoptotic cells (A) was also included for comparison. Letters and Roman numerals with arrows indicate the fragments observed, some of which are only observed with very short exposure times (fragment A of β-catenin in panel b).