Perk Inhibitor III, LDN-0070977

A major focus of breast cancer research is to understand the mechanisms responsible for disease progression and drug resistance. Toward that end, it has been found that approximately two thirds of all human breast carcinomas overexpress the Estrogen Receptor α (ERα) protein and it remains the primary pharmacological target for endocrine therapy1,2. The normal cellular function of ERα is as a transcription factor that mediates a wide variety of physiological processes, many of which are dependent upon phosphorylation of the receptor at specific amino acid residues3,4. Indeed, ERα is known to be phosphorylated at a multitude of different sites, yet how these all correlate to disease remains unclear5. Here, we interrogated multiple sites of ERα for phosphorylation status by screening an extensive panel of different breast cancer patient samples and other non-breast cancer tissue microarray (TMA) slide samples to determine their relevance to disease.