Something is Wrong with the Computer

woah its red

Ah cell medium, a very fraught subject in biology. Two quick points that were not covered, or not covered very well in the article. First, the red color comes from a chemical, phenol red, that is used to monitor pH. If the solution gets too acidic it turns yellow, too basic and it turns purple. Although phenol red has been used forever, it is a slight estrogen mimic, which can alter how the cells work, especially if you are looking at estrogen receptors, but you can get EMEM and DMEM without phenol red.

Second, the article dosen't really talk about another important part of cell media, FBS or fetal bovine serum. This is added to the cell growth media to provide important hormones (like insulin) and other growth factors (which aren't completely understood) to the cells. This is an animal product which varies from batch to batch, and you can see how this causes issues in repeat-ability, as well as not being a human product for studying human cells.