Indeed, without any external stimulus, microtumors derived from select cancer cell lines develop three key hallmarks of tumor progression observed in vivo: increasing microtumor size drives hypoxia and metabolic stress; heterogeneous tumor cells expressing different levels of E-cadherin (epithelial marker) and vimentin (mesenchymal marker) spontaneously emerge; and peripheral cells begin to migrate from the parent tumor. Here, VIM is linked to neoplasm.