Fig. 1

Illustration of the differences between a tumor cell-derived tubule-like structure and a vessel-like structure. a A cross section of a tubule-like structure showing multiple cuboidal cells forming a tubular structure. This kind of structure might be able to express different proteins in the apical membrane (red) and basolateral membrane (green). Polarization of nuclei (yellow) might be observed. b A longitudinal section of a vessel-like structure showing elongated cells with alternative staggered distribution of the nuclei, resulting in only one nucleus or no nucleus in any cross section. Notably, the rod-like structure of the nuclei indicates the trans-differentiation tendency from cancer cells to the cells forming blood vessel. Moreover, the vessel lumen (light blue) might be absent depending on different stages of development