CASP9 and esophageal squamous cell carcinoma: Wang et al. [41] employed a TMT-based quantitative proteomic approach to identify PAR4-regulated proteomic profiles in ESCC cells and showed that key higher expressed proteins included those linked with apoptosis and tumor suppressors (e.g. caspase 9), and lower expressed proteins included those linked with anti-apoptosis, autophagy and enhancing cell proliferation.