The functions of the DEGs in epithelial subcluster 2 between PTC1 and PTC2 were analyzed, and the top 30 pathways are shown in Fig. 4C. The results show that some pathways associated with carcinogenesis, such as the HIF-1 signaling pathway and the thyroid cancer pathway, were enriched in upregulated genes in PTC2 (Fig. 4C). The gene discussed is PTCH2; the disease is thyroid cancer.