RB1 and obesity due to melanocortin 4 receptor deficiency: Also, although total Rβ expression was unchanged with obesity, OB exhibited higher Rβ expression in Tyr-phosphorylated form; importantly, Losartan increased Tyr-phospho-Rβ form expression in both L groups (C 1.00±0.15; OB 1.61±0.29; CL 1.87±0.23; OBL 2.32±0.20AU; Figure 5).