MEC1 cells injected subcutaneously grow and substantially localize in several organs of Rag2^−/−γ_c^−/− mice. (A) Rag2^−/−γ_c^−/− male mice received a transplant subcutaneously in the left flank of MEC1 cells with or without GFP expression (10 × 10⁶ cells/mouse; n = 4, repeated twice), showing no significant difference in tumor engraftment. Tumor size was evaluated by measuring perpendicular diameters by a caliper. Animals were killed when the tumor volume reached 1000 mm³. (B) Organs from these animals were collected and analyzed macroscopically. (C) Peripheral blood was extracted from Rag2^−/−γ_c^−/− male mice injected subcutaneously with MEC1 cells expressing GFP and killed when the tumor volume reached a dimension of 1000 mm³. The dot plot analysis shows the intensity of the staining with monoclonal antibody (mAb) against human CD19, after gating on the GFP⁺ leukemic B-cell population. (D) Peritoneal exudate was extracted from Rag2^−/−γ_c^−/− male mice injected subcutaneously with MEC1 cells expressing GFP and killed when the tumor volume reached a dimension of 1000 mm³. The dot plot analysis shows the intensity of the staining with mAb against human CD19, after gating on the GFP⁺ leukemic B-cell population.