Interestingly, of the 14 keratin genes that are differentially expressed between C1 and C2 tumours, three (KRT7, KRT8 and KRT18) that are upregulated in C2 were classified as marker genes for columnar-like tumours with a possible endocervical origin in a recent study that used single cell RNA-sequencing and lineage tracing experiments to explore cell-of-origin for CSCC and adenocarcinoma75. Here, KRT18 is linked to neoplasm.