In this task, you are given a sentence. You are expected to recognize the name of gene or protein. Although there might be several correct answers, you need to write one of them.
Q: A significantly positive correlation was found between ST1 expression , and p53 tumour suppressor gene product ( p = 0 . 004 ) , and a relationship with c - erbB - 2 protein and progesterone receptor status was also indicated .
A:
progesterone receptor