To chart the cell ecosystem of CRC and how it changes during tumor progression, we studied two genetic mouse models of CRC, one with inactivation of Apc and another in which Apc inactivation is accompanied by an oncogenic KrasG12D/+ mutation and inactivation of Trp53 (Roper et al., 2017; Roper et al., 2018; Golovko et al., 2015; Figure 1A). The gene discussed is APC; the disease is neoplasm.