Igure 1A). Imatinib treatment induced endogenous IGFBP3 expression by 24 hours after treatment, and the induction was maintained at 48 hours post-treatment (Figure 1B). Because IGFBP3 is a secreted protein that can be re-internalized into the cell [25], we used an ELISA to determine if elevated levels of IGFBP3 were also present in the cell culture medium after imatinib exposure. As shown in Figur