ERBB3 and thyroid gland carcinoma: For instance, in 8505C cells vemurafenib treatment increases pHER2 and pHER3 levels, whereas pEGFR levels decline (Fig. 4F), consistent with previous evidence that HER3/HER2 heterodimers are the primary mediators of ERK rebound in BRAF-mutant thyroid cancer cells [2].