[pS2 protein and breast cancer].

pS2 is a small protein (7000 daltons) that is prevalently expressed in human breast cancer positive for estrogen receptors: protein is, in fact, induced by estrogen stimulation. Studies indicate that pS2 protein is a marker for hormone-dependent breast tumors and that its expression is helpful in the prognosis. The presence of pS2, in fact, besides being associated in 96% of the cases to the positivities for estrogen receptors, is associated with longer overall, and disease free, survival. The pS2 protein is also expressed in normal stomach mucosa; its physiological function is unknown.