Cell lines are distinguished by their nutritional, growth factor, and inorganic supplement needs, as well as subculture routines, optimal cell concentrations, doubling times etc. To assist users we regularly reappraise growth parameters and up date web data as necessary.

The cell lines in the collection are usually cultured as recommended by depositors. However, in a few cases we have found it necessary to modify original FBS concentration, optimal cell densities, culture vessels, nutritional supplementation etc. to simplify culture. These modifications are included in the data sheets. As cell lines are living material, we usually specify typical values which are, of course, subject to biological variability. We generally omit antibiotics in our culture media to unmask patent contaminations and obviate selection for resistance. We recommend users do likewise unless absolutely necessary.

Special attention is paid to the growth factor dependency among cell lines. The growth factor responsiveness of growth factor dependent cell lines is verified for each lot by 3H-thymidine assay to avoid selection for autonomous growth. Users are advised to avoid over-diluting such cell lines lest bottle-necking selection for growth-factor independence occurs.

We do not specify passage numbers. In most cases we have no information on the passage number when we receive a cell line. As far as we know, collection cell lines are immortal, rendering passage numbers biologically irrelevant. Moreover, passage numbers should never be equated with generation number due to wide variations in split ratios and subculture intervals encountered.