RPS6KA1 and obesity due to melanocortin 4 receptor deficiency: Overall, adiponectin plays a negative regulatory role in maintaining a balance of cell numbers through inhibiting the MEK-ERK-p90RSK axis; adiponectin deficiency occurs in the condition of obesity and leads to abrogation of this negative regulatory effect and imbalance between cell growth and death, further resulting in the development of BPH (Fig. 8).