IGF1 and esophageal squamous cell carcinoma: In order to assess whether downregulation of IGFBP5 results in hyperactiviation of the IGF-signaling pathway and in turn confers cisplatin-resistance to ESCC, investigation of the status of IGF-signaling in SLMT-1/CDDP1R compared with parental SLMT-1 is suggested in future studies.