Fig. 2.

Synergistic effects of erlotinib and cisplatin on SKOV3 and OVCAR3 cell lines. (A) SKOV3 and (C) OVCAR3. (B and D) Normalized isobologram analysis represents the synergic effect of erlotinib (2 µM) and cisplatin (0.1, 0.5, 1, 2.5, 5, 10, and 25 µg) when using combination treatment in SKOV3 and OVCAR3 cell lines. The combination index was calculated with Calcusyn software. Points above, below, and over the isobologram effect line reflect antagonism, synergy, and additive effect, respectively. The numbers under the isobolograms indicate the doses of erlotinib and cisplatin in combination. Statistically significant values of ^*p < 0.05, ^**p < 0.01, and ^***p < 0.001 were determined compared with the control