ERBB3 and breast cancer: Because our previous studies showed that Th1 cytokines could drive down both HER-2 and HER-3 expression on multiple breast cancer cell lines [6], we hypothesized that Th1 cytokines and lapatinib would work well together; cytokines to diminish total HER expression, and lapatinib to block the activation of the remaining expressed HER family RTKs.