Using the wrong media - (Feb/10/2014 )
Yesterday I saw that my transfected 24 well cells' media looked yellow. The cells are 293t cells. So I decided to add in fresh serum free media. Instead of using DMEM I accidentally used RPMI instead. Will this ruin my experiment?
General rule - If in doubt, throw it out. It may not affect your experiment (it's hard for someone else to know when you don't provide any details of what you are doing), but how will you know that it didn't - if you repeated it and got a different result, how would you know which one is correct?
I would say, if the cells have been in the wrong maintenance media for a short time (say about a day), it might be Ok. 293 are very hardy cells and they probably don't really care. The one time I'd DEFINITELY throw out the experiment and start anew, is if the wrong medium was not a maintenance medium, but some sort of differentiation or other specialty medium.
Hope this helps.