LGR5 and colorectal carcinoma: In order to focus on tumors that display preserved hierarchical organization, we focused on the eight cultures with detectable LGR5 transcript levels (LGR5 score = total LGR5 transcript counts/cell number > 1; Table 2), as LGR5 represents an established marker for intestinal stem cells and CRC TICs, whereas the phenotype and the role of potential LGR5-negative stem cells and TICs are much less defined [8,14,26,27].