Absence of <i>Inca1</i> accelerates MLL-AF9 driven murine leukemogenesis.

<p><b>A.</b> Survival curves of recipient mice, which were transplanted with bone marrow cells of <i>Inca1^+/+</i> or <i>Inca1^−/−</i> mice that were retrovirally transduced with MLL-AF9 as depicted in Fig. 4A (n = 11 of each genotype). Cells of both genotypes led to a fatal leukemic disease with comparable latency. <b>B.</b> Survival curves of secondary recipient mice which were transplanted with 10⁶ GFP⁺ leukemic spleen cells of leukemic mice derived from the primary transplantation shown in Fig. 5B. The secondary recipients of <i>Inca1^−/−</i>; MLL-AF9 cells (n = 15) died after a significantly longer latency than mice transplanted with <i>Inca1^+/+</i>; MLL-AF9 primary blasts (n = 15; p<0.001). Secondary transplantation of <i>p16^−/−</i>; MLL-AF9 blasts also had elongated survival compared to wild type-MLL-AF9 cells (p<0.001), but to a significant less extent (<i>Inca1^−/−</i> vs <i>p16^−/</i>−: p<0.001). <b>C.</b> Colony assays using MLL-AF9/GFP⁺c-kit⁺<i>Inca1^+/+</i> or <i>Inca1^−/−</i> spleen blast, respectively. <i>Inca1^−/−</i>; MLL-AF9 blasts formed less colonies <i>Inca1^+/+</i> blasts (p = 0.05, t-test). <b>D.</b> For a cloning efficiency assay, <i>Inca1^+/+</i>; MLL-AF9 or <i>Inca1^−/−</i>; MLL-AF9 bone marrow cells from leukemia-transplanted mice were FACS-sorted and 1 to 300 c-kit⁺GFP⁺ cells were seeded in semi-solid medium in a 48-well plate. <i>Inca1^+/+</i> cells had a clone forming frequency of 1/13, while the frequency was much lower in <i>Inca1^−/−</i> cells (1/54; p = 0.0001). Shown here are the mean results of two independent experiments.