ERα, PR, IL-6 and IL-8 protein expression determined by proximity ligation assay (RT-Protein PCR). dCt values were obtained by subtracting sample Ct values from no protein control values. In contrast to gene expression, for protein PCR results, increases in dCt values correlate with increased protein expression. A) Detection of proteins in ERpos MCF7 and T47D cells and ERneg HCC 1806 cells at titrations of 250, 125, 62, 31 cells. Benign sample 84 M was used to determine titration for detecting IL-6 protein (cell titration 5000, 2500, 1250, 625, 313, 156, 78, 34 cells). Black symbols: benign tissue samples, red symbols: IHC designated ER positive IDC tumor samples, blue symbols: IHC designated ER negative IDC tumor samples. B) Protein detection in pulverized (Pulv) versus enzyme treated (Enz) tumor or tissue lysates. C-F) Protein detection normalized to 250 cells, C) ERα, D) PR, E) IL-6, and F) IL-8. Grey box indicates values considered equivocal. * indicates p < 0.05, for populations compared by bracket.