IGFBP3 and esophageal squamous cell carcinoma: To test this hypothesis, we first validated that knockdown of IGFBP3 partly reversed the inhibitory effects of PURα loss on ESCC progression, especially cell proliferation, migration and invasion (Fig. 6A–D), and observed that the expression of PURα was negatively correlated with IGFBP3 expression in ESCC tissues (Fig. 6F, G), which further supported that IGFBP3 was partially required for PURα to regulate ESCC progression.