Percentages of cell survival compared to vehicle control following 6 days of treatment with eribulin at indicated concentrations, either alone or in combination with BKM120 (500 nM) were plotted for (A) BT549, (B) MDA-MB-231, (C) HCC1806, (D) WHIM3, and (E) WHIM12. * indicates p<0.05 and ** indicates p<0.01. The combination of BKM120 and eribulin was significantly more effective in reducing cell survival than each agent alone in these cell lines. Panel F shows the Western blot analysis for PI3K pathway signaling, EMT, and apoptosis markers on cell lysates from BT549 and MDA-MB-231 following treatment with eribulin and BKM120, alone or in combination for 48 hours. Abbreviations: V, Vehicle; B, BKM120; E, Eribulin; C, Combination. Compared to single agents, the combination of BKM120 and eribulin was most effective in reducing the levels of pAKT and pS6 (markers of PI3K pathway activity), N-Cadherin (EMT marker) and Survivin (an anti-apoptotic protein) and in the induction of apoptosis (Cleaved PARP).