LC–MS/MS analysis of IP pull-down proteins using anti-PIK3IP1 antibodies revealed that the potential PIK3IP1-interacting proteins included five de-ubiquitinating enzymes, among which the ubiquitin-specific protease 14 (USP14) protein had the highest abundance in ESCC cells (Fig. 8A–C). The gene discussed is PIK3IP1; the disease is esophageal squamous cell carcinoma.