L-leucine administration has no effect on mTOR but dampens the p53 activity in hematopoietic progenitors. (A) Flow cytometric quantification of phospho-Rps6 (Ser235/236) and phospho-4E-BP1 (Thr37/46) in myeloid progenitors (CD11b⁺c-Kit⁺), proerythroblasts (Ter119^lowc-Kit⁺CD11b⁻), and mature erythroid precursors (Ter119⁺CD11b⁻c-Kit⁻) on day 14 (n = 6, 3, 5, and 7 for control, control + L-leucine, [D/D], and [D/D] + L-leucine, respectively). Mean fluorescence intensity relative to that of isotype control is presented. (B) p53 transcriptional targets were quantified using real-time PCR in preCFU-E/CFU-E and preGM/GMP populations sorted from individual mice on day 14 (n = 5, 13, and 13 for control, [D/D], and [D/D] + L-leucine, respectively). Error bars represent SD.