We have encountered a problem during our transient transfections of HeLa
cells. The problem is that we only get measureable expression within
2 weeks of thawing a new batch of cells. The problem is not due to low
expression levels from our promoter as it is very strong whenever we use
freshly thawed cells. Instead we suspect that our transfections only
work withfresh cells. As it is a pain to freeze and thaw and grow cells all
the time we welcome any suggestions.