LEP and leukemia: In particular, the enhanced leukemic engraftment in this setting might be due to the enhanced fat content of the BM with increased leptin and CXCL12 expression, possibly overruling a negative effect of CCN2 deficiency, as leptin enhances leukemic cell growth (Konopleva et al. 1999; Tabe et al. 2004) and CXCL12 is a known homing factor for leukemia cells (Möhle et al. 2000).