GPX3 and obesity due to melanocortin 4 receptor deficiency: Recently, GPX3 has been recognized as a novel regulator of insulin receptor expression, insulin receptor and GPX3 expression were positively correlated in mouse models of obesity and insulin resistance: By activating the transcription factor SP1, GPX3 promotes insulin receptor expression in 3T3-L1 preadipocytes and improves adipose tissue insulin sensitivity.