PNLIP and obesity due to melanocortin 4 receptor deficiency: Our results align with earlier studies showing that PTL activates the Nrf2/Keap1 axis through elevating Nrf2 and suppressing Keap1 protein contents in adipocytes in an obesity-induced inflammatory response model (Kim et al. 2019), and in an adipocyte differentiation model (Kim et al. 2020).