On the one hand, the Epi1 cluster may give rise to the malignant squamous cell subclusters Epi7 and Epi8, with increased expression of the malignant markers MKI67 and TOP2A. On the other hand, Epi1 can also differentiate into the squamous cell subcluster Epi5, which shows more differentiated characteristics, including high expression of SPRR3 and SPRR2a. Furthermore, cell cycle analysis of epithelial cells revealed that these epithelial cells were gradually activated along the tumorigenic trajectory, thereby further confirming the tumorigenesis of CESC [20]. This evidence concerns the gene TOP2A and cervical squamous cell carcinoma.