VOPP1 and squamous cell carcinoma: VOPP1, also known as glioblastoma-amplified secreted protein (Dunham et al., 2012) and EGFR-coamplified and overexpressed protein (ECOP) (Fang et al., 2020), is upregulated in multiple human tumors, such as gastric cancer and squamous cell carcinoma (Baras et al., 2011; Gao et al., 2015).