IGFBP3 and neoplasm: Treatment of IGFII up-regulates Igfbp3 expression in KrasG12D/+; p53f/f; Ng2/Cspg4+/+ tumor cells, but this stimulatory effect is lost in the KrasG12D/+; p53f/f; Ng2/Cspg4f/f tumor cells (Fig. 5C).