3.3.1. IGFBP-2

As a main effect of age in all female mice, IGFBP-2 was reduced between weeks 2 and 4 (*p* < 0.01), increased between weeks 4 and 11 (*p* < 0.001), and reduced between weeks 11 and 16 (*p* < 0.001; Figure 3). As an effect of age in all male mice, IGFBP-2 also was reduced between weeks 2 and 4 (*p* < 0.001), increased from week 4 until week 16 (*p* < 0.001), and then decreased from week 16 to week 26 (*p* < 0.001). The effects of age in selected mouse lines are depicted in Figures 3 and 4 (interactions of age and genetic group).

**Figure 3.** Concentrations of insulin-like growth factor binding protein (IGFBP) -2, -3, and -4 in serum from female mice selected for high body weight (obese), for high protein amount (lean), and in unselected controls at an age of 2, 4, 7, 11, 16, 29, 42, and 54 weeks (mean ± SEM; n ≥ 7; different letters (a and b) indicate significant effects also if different genetic groups were compared; identical letters indicate no statistically significant difference; \*\*: *p* < 0.01; \*\*\*: *p* < 0.001).

**Figure 4.** Concentrations of IGFBP-2, -3, and -4 in serum from male mice selected for high body weight (obese), for high protein amount (lean), and in unselected controls at an age of 2, 4, 7, 11, 16, 29, 42, and 54 weeks (mean ± SEM; *n* = 8 with the exception of obese male at an of 42 weeks and 54 weeks with *n* = 7 and *n* = 4, respectively; different letters (a and b) indicate significant effects of age; identical letters indicate no statistically significant difference also if different genetic groups were compared; \*: *p* < 0.05; \*\*: *p* < 0.01; \*\*\*: *p* < 0.001).
