ERBB3 and cancer: Reverse phase protein array (RPPA) analysis was performed on enriched tumor cell lysates to quantify a 32-protein/phosphoprotein biomarker panel comprising known anticancer drug targets and/or cancer-related total and phosphorylated proteins, including HER2<sup>Total</sup>, HER2<sup>Y1248</sup>, and HER3<sup>Y1289</sup>.