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.

Similarly , anti - IgM stimulation resulted in enhanced tyrosine phosphorylation of STAT5A in BTK - competent B cells from wild type mice but not in BTK - deficient B cells from XID mice .
anti - IgM