RanBP10 depletion is partially compensated for by overexpression of RanBP9 but does not influence platelet turnover, MK numbers or receptor expression. (A) RanBP9 mRNA expression is up-regulated in spleen and CD61⁺ cells of RanBP10-null mice. Expression levels were analyzed by quantitative real-time PCR and were normalized to GAPDH. (B) Bone marrow MKs were stained with PI and ploidy evaluated by flow cytometry. The amount of 16N-64N MKs is significantly elevated in RanBP10^−/− mice compared with controls. (C) The amount of bone marrow MKs is slightly elevated in mutant mice. (D) Platelet life span in vivo is unaltered in mice lacking RanBP10 (*P < .05).