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.

To study the mechanisms and the signaling pathways involved , IGF - 1R promoter reporter constructs were transiently transfected in CHO - AT1 cells that overexpress angiotensin AT1 receptors .
angiotensin AT1 receptors