ESPL1 was previously found to be overexpressed in lung adenocarcinoma smoking patients (He et al. 2018), and Zhang et al. suggested that it may be combined with other genes including BUB1 and E2F1 to form a regulatory network causing abnormalities of cell proliferation, transport and metabolism hence facilitating tumour progression (Zhang et al. 2016). This evidence concerns the gene E2F1 and lung adenocarcinoma.