Lapatinib resistant lines are resensitized to drug in the presence of Th1 cytokines.

A) Cultured SK-BR-3, HCC1419, JIMT-1, and MDA-MB-453 cells were treated either with Th1 cytokines (TNF-α plus IFN-γ; 20 and 12.5ng/ml respectively), Lapatinib (0–4μM), or Lapatinib plus Th1 cytokines. After 72 hours incubation, resazurin sodium salt was added to each well and further incubated until color change was noted, and optical densities of supernatants read spectrophotometrically at 630nM. B) Statistical analysis at 2μm concentration of lapatinib. Shown are composite data from at least three trials per cell line expressed as mean optical density +/- SEM. Statistical significance was determined by one-way ANOVA followed by the Holm-Sidak multiple comparison test.