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 increments in median plasma secretin concentration were 1 . 6 , 3 . 0 , and 6 . 4 pmol x 1 ( - 1 ) after secretin , 125 , 250 and 500 fmol x kg - 1 , and the corresponding 15 - min bicarbonate output 283 , 442 , and 1435 micromol , respectively .
plasma secretin