LCP1 is critical to bone marrow migration of leukemia in an in vivo xenotransplantation model. (A) CB17/SCID mice were engrafted with 1E7 live 697-parental, 697-Empty Vector, or 697-LCP1 shRNA cells and sacrificed on day 18. Bone marrow infiltration of GFP⁺human-CD19⁺ cells was quantified by flow cytometry. Bars depict average bone marrow infiltration of CD19⁺ cells. Error bars indicate standard error of the mean (B) H&E stained sections of femoral bone marrow from 697-Empty Vector (left), note the bone marrow in this photomicrograph is largely replaced by a monomorphic population of neoplastic round cells containing numerous mitotic figures (arrows). Low-magnification view of the neoplastic cell population (N), which is invading and replacing normal hematopoietic bone marrow (H), as compared with sections from 697-LCP1 shRNA (right), which depict significantly less pathology than the control group. This photomicrograph depicts normal bone marrow in a mouse from this group. Several megakaryocytes (arrowheads) are surrounded by myeloid and erythroid precursor cells. Controls (bottom row) included a mouse engrafted with the parental 697 cell line and an animal that received no xenograft.