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.

Example input: Sox - 4 is important for very early B - cell differentiation , while TCF - 1 / LEF - 1 play a crucial role in early thymocyte development
Example output: TCF - 1
Example explanation: The gene, TCF - 1 has been tagged as protein since it plays a crucial role in early thymocyte development.
Q: The goals of these experiments were to determine whether lactational anestrus would be prolonged by a 48 - h fast at days 13 and 14 postpartum ( pp ) and , if so , to determine whether this effect could be reversed by treatment with the Ob protein leptin .
A:
Ob protein