Figure 2.

P-1257 peptide affecting PI3K/Akt and MAPK pathways favors Trastuzumab responsiveness and induces apoptosis. (a–c, left panels) JIMT-1, KPL-4 and BT474 parental cells, transiently transfected with P-scr or P-1257 peptides, were maintained in the presence or absence of Trastuzumab. Total cell extracts were analyzed by immunoblotting with ErbB-3, ErbB-2, P-Akt and P-ERK1/2 antibodies. Antibodies specific for Hsp-70, total Akt and ERK1/2 were used for loading control. (a–c, right upper panels) cell viability was evaluated by Trypan blue exclusion. Percentage of cell death was evaluated from three independent experiments; bars±S.D. (a) Right panel, JIMT-1 cells: ***P<0.0002; and *P<0.01. (b) Right panel, KPL-4 cells: ***P<0.0006 and *P<0.05. (c) Right panel, the cell death evaluated in BT474 cells was not significantly different between P-1257 and P-1257+T versus T alone or P-scr+T. (a–c, right lower panels) Total cell extracts were analyzed by immunoblotting with anti-intact human PARP antibody and anti-Hsp-70 for loading control