Antibody-mediated inhibition of EGFR and HER2 in response to EGF stimulation. Phospho-RTK arrays were used to assess the relative phosphorylation of EGFR (black bars) and HER2 (lined bars) from EGF-stimulated tumor 366 cells following 90 minutes of drug treatment with DMSO, panitumumab (5 μg/ml), trastuzumab (20 μg/ml), trametinib (10 nM), or the indicated combination therapy (+ indicates drug present and − indicates drug absent). Images from the pRTK arrays used to assay relative phosphorylation level are depicted below each treatment group. Images were cropped and aligned from individual arrays exposed for the same period of time for ease of comparison with vertical bars separating individual arrays. The mean pixel density of two replicates for each phospho-antibody was quantified, normalized to control, and depicted in bar graph form. Image acquisition and analysis were performed using a Bio-Rad GS-800 calibrated densitometer and ImageQuant TL 2005 software. Significant difference in mean pixel density for each treatment group compared to control is denoted as *P < .05. Figure W1 shows the complete array images.