You will be given a definition of a task first, then some input of the task.
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.

 It appears that the binding sites of albumin provide a mechanism for retarding androstenedione uptake by the erythrocytes and that the high binding affinity of SHBG for testosterone facilitates the diffusion of this steroid out of the cell and thus , displaces the chemical equilibrium within the cell .
Output:
binding sites