cell line A cultured cell population that represents a genetically stable and homogenous population of cultured cells that shares a common propagation history (i.e. has been successively passaged together in culture). He, Tong-Chuan, et al., Identification of c-MYC as a target of the APC pathway. Science 281.5382 (1998): 1509-1512.: "To evaluate the transcriptional effects of APC, we studied a human colorectal cancer cell line (HT29-APC) containing a zinc-inducible APC gene and a control cell line (HT29–β-Gal) containing an analogous inducible lacZ gene". Note that common usage in the literature is often of the form "a human colorectal cancer cell line", as seen above. But such references to studies in "a line" refer to the fact that discrete populations of cells that are input into culturing or experiments, not an entire lineage of cells. It is these discrete populations that we refer to as 'cell lines'. A cultured cell population that represents a genetically stable and homogenous population of cultured cells that shares a common propagation history (i.e. has been successively passaged together in culture). secondary cultured cell population