Given the task definition and input, reply with output. 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.

The unagglutinated thymocytes ( peanut negative ) contained about 2 times more receptor sites per cell than agglutinated ( peanut positive ) ones ( 7650 + / - 1550 S . D . verus 3195 + / - 896 S . D . ) .
receptor sites