Wild type and TgAPT121 mice were fed diets with increasing levels of vitamin D from weaning followed by castration (Cast) and testosterone repletion (Cast + TP). Serum was analyzed for (A) 25OH D, (B) 1,25(OH)2 D, and (C) calcium. Bars are the mean ± SE of the combined wild type and TgAPT121 mice data, n = 12. Bars without a common letter are significantly different, P<0.05.