If cell-based work was not difficult enough, a recent article by Liu and coworkers (1) there is extensive variation in variout stock HeLa cell samples obtaine from a group of international laboratories. This would suggest that extensive characterization of HeLa cells (and other cells. Cell banks should be subjected to extensive characterization on an annual basis.

1, Liu, Y., Mi, Y,, Mueller, T., et al., Multi-omic measurements of heterogeneity in HeLa cells across laboratories, Nature Biotechology 37(3), 314-322, 2019