BCL2 and leukemia: Uncoupling and chemoresistance are exacerbated in leukemia cells cultured on mesenchymal stromal feeder layers (Samudio et al., 2008), and previous reports indicate that stromal coculture upregulates Bcl-2 and Bcl-xL in leukemia cells (Konopleva et al., 2002) suggesting that the leukemia microenvironment promotes chemoresistance via, in part, by potentiation of the antiapoptotic function and/or expression of Bcl-2 family members.