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G-induced IGFBP3 expression. As shown in Figure 4B, si-IGFBP3 effectively reduced IGFBP3 mRNA levels in untreated cells and also prevented IGFBP3 induction after imatinib exposure. Loss of IGFBP3 protein expression after imatinib was also observed (Figure 4C). Using thissiRNA, we investigated whether inhibiting IGFBP3 expression altered GIST882 cell sensitivity to imatinib. IGFBP3 knockdown itself