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 explain the end - organ resistance to cortisol , the glucocorticoid receptors ( GR ) in peripheral mononuclear leukocytes and cultured skin fibroblasts from a forearm skin biopsy were characterized and compared with the results of similar studies in normal subjects .
glucocorticoid receptors