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.

Expression of the granulocyte - macrophage colony - stimulating factor ( GM - CSF ) gene in T cells is activated by the combination of phorbol ester ( phorbol myristate acetate ) and calcium ionophore ( A23187 ) , which mimic antigen stimulation through the T - cell receptor .
GM - CSF