CD34 and B-cell chronic lymphocytic leukemia: As the first transgenic mouse model of CLL was generated by overexpressing the human TCL-1 gene under the control of the immunoglobulin heavy chain variable region promoter and immunoglobulin heavy chain enhancer [19], we transduced CD34+ human hematopoietic progenitor cells with TCL-1-expressing lentivirus before injecting these cells into the neonatal mice.