RPS6KB1 and obesity due to melanocortin 4 receptor deficiency: Most interestingly, a negative correlation was seen between hsa-miR-221-3p levels and levels of RPS6KB1 (p70S6K), which has been associated with insulin sensitivity, aging, and obesity, and serine/threonine-protein phosphatase PP1-beta catalytic subunit levels, which are known to participate in glycogen metabolism.