To elucidate whether Treg depletion was important to the therapeutic effectiveness of CPM, vav-BCL-2 transgenic mice, in which all hematopoietic cells overexpress BCL-2 and are resistant to apoptosis (Egle et al., 2004; Ogilvy et al., 1999), were inoculated with 9464D tumor and treated with low-dose CPM as above. This evidence concerns the gene VAV1 and neoplasm.