These data indicate that the vast majority of alterations in peripheral protein concentrations arise due to the presence of a growing renal tumor and are minimally impacted by obesity, with the exception of IGFBP-1, which was previously reported to be decreased in subjects with obesity versus those who were non-obese [29, 30] as we validate here. Here, IGFBP1 is linked to obesity due to melanocortin 4 receptor deficiency.