Proposed model of leukemic CLL B cell and stromal cell interaction. This model indicates that CLL secrete PDGF into the microenvironment. PDGF can then bind to the PDGFR in MSCs to trigger downstream PI3K-Akt activation. PDGFR-PI3K-Akt activation further triggers downstream signal pathways that result in increased VEGF production, which subsequently leads to increased survival/drug resistance in CLL cells, as well as promoting neovascularization. See “Discussion” for more details regarding this proposed model.