A TMA study [51], using tumour samples from 200 breast cancer patients, was conducted that focused on HDAC-1 and HDAC-3, from HDAC class I, since these play a role in proliferation and cell survival of mammary tumour cells and can interact either directly or indirectly with the steroid hormone receptors ER and PGR as well as the tumour suppressor p53 [[52-54]]. The gene discussed is ESR1; the disease is neoplasm.