CD19 and B-cell chronic lymphocytic leukemia: Given the strong, selective effect observed ex vivo, we then tested PAPTP in Eμ-TCL1 mice in vivo CLL in humans is characterized by clonal expansion of small, mature-looking CD19+CD5+ B cells and by their accumulation in the blood, bone marrow, and lymphoid organs; we thus assessed the effect of PAPTP in vivo in various body districts and tissues in Eμ-TCL1 mice where the same CD5+ B cell clone localizes to bone marrow (BM), spleen, peritoneal cavity and peripheral blood (PB) [36].