AGTR1 and obesity due to melanocortin 4 receptor deficiency: Because it was reported that angiotensin II (ANG II) is one of the peptide hormones induced by aging and obesity [3] and that chondrocytes express it two specific receptors, angiotensin II receptor type 1 (AT1R) and type 2 (AT2R) [4], we focused on ANG II functions in chondrocytes in this study.