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.

[EX Q]:  No evidence for the existence of a specific progesterone receptor in human mononuclear leukocytes was obtained as judged by the results of competition experiments where a progesterone receptor - specific ligand [ 3H ] Org 2058 was used .
[EX A]: progesterone receptor

[EX Q]:  Tumors binding more than 5 fmol / mg cytosol protein were classified as ER - positive .
[EX A]: cytosol protein

[EX Q]:  Pax5 thus functions both as a transcriptional repressor and activator , depending on its interactions with corepressors of the Groucho protein family or with positive regulators such as the TATA - binding protein .
[EX A]:
Groucho protein family