Analyses of v-Abl and MAPK phosphorylation on 32D neo and β4 transfectans.

(A) Total cell lysates from 32D/v-Abl/neo cells (lane 1), 2 derived 32D/v-Abl/β4 clones (lanes 2 and 3), and 32D/v-Abl/β4 L clone (lane 4), were immunoprecipitated with anti–Abl monoclonal antibody. The immunoprecipitated Abl proteins were analyzed by SDS-PAGE and probed with antiphosphotyrosine monoclonal antibody (upper panel A). The nitrocellulose was stripped and probed again with the anti–Abl polyclonal antibody (lower panel A). (B) Total cell lysates from 32D/neo (lane 1), 32D/β4 (lane 2), 32D/v-Abl/neo (lane 3), 32D/v-Abl/β4 (lanes 4 and 5), and 32D/v-Abl/β4 L cells (lane 6) were analyzed by SDS-PAGE and probed with an antibody to the active doubly phosphorylated forms of the MAPK (ERK 1 and 2) (upper panel B). The nitrocellulose was stripped and probed again with an antibody specific to the native unmodified form of ERK/MAPK (lower panel B).