MMP2 and neoplasm: The pathway analysis revealed that the epithelial mesenchymal transition (EMT) pathway, which was associated with many processes in tumor including tumor initiation and metastasis [47], was most significantly up-regulated in hybrid cell-derived tumor cells in vivo and in vitro (Fig. 7a–c), and the marker genes involved in EMT, including Cdh2 (N-Cadherin), Mmp2, Mmp3, Vim, and Spp1, were highly expressed in hybrid tumor cells (Fig. 7e), which suggested hybrid cells might have a stem-like phenotype with high metastatic and tumorigenic potential in vivo.