IGF-IR and EGFR/Her-2 inhibition decreases the viability of pancreatic tumorspheres. (A) Basal levels of IGF-I and ErbB receptors and their signaling pathway components in BxPC3 and CP15T tumorspheres were determined by Western blot. M, monolayer; T, tumorspheres. (B) Dose–response curves and IC50 values for NVP-AEW541 and lapatinib. Cells were seeded with increasing concentrations of NVP-AEW541 or lapatinib, and cell viability was measured by WST-8 assay 72 h after initiating treatment. ● BxPC3, ■ CP15T (C) Dose–response curves and CDI values for NVP-AEW541 and lapatinib combinations. Cells were seeded with increasing concentrations of lapatinib alone (●) or combined with a fixed concentration of NVP-AEW541 (▲) equivalent to its IC20. Data are presented as means ± standard deviation of three experiments.