CCNA2 and neoplasm: The ‘tumor cells 1’ cluster had the gene expression characteristic of stem-like tumor cells with an elevated expression of genes involved in cell division and chromosome segregation such as Top2a, Mki67, Cenpf, Cenpe, Incenp, Anln, Ccna2, Kif20b, Ccnb1, and Smc4 (Figure 3A) [22].