Highlights of the results of total cellular protein assay on pY peptide microarray.

<p>(<b>a</b>) Phosphopeptide microarray images showing spots of GRB2 association with specific phosphopeptide probes that represent phospho-motifs that are upregulated in ER positive breast tumor cells (MCF7 and T47D) compared to normal (MCF10A) or metastatic (MDA-MB231) cells that are ER negative. (<b>b</b>) Heatmap comparing high confidence GRB2 interactions from normal breast epithelial (MCF10A), breast tumor (MCF7, T47D) and metastatic (MDA-MB231) cell lines. The binding signals were normalized into Z values. The PPEPs with Z values ranked from 1.0–3.0 were selected to plot the heat map. The heat map clearly indicates upregulation of GRB2 interactome in tumor cells compared to normal or metastatic cells.