I have cultured cells which were exposed to a certain drug in a 24 well plate at different conc and time points. At the end of the experiment, I used Trizol for RNA isolation. I removed media from each well first, then added Trizol to each well, pipetted up and down and added those lysed cells to fresh tubes. Then I followed RNA isolation protocol. Briefly, I added chloroform and centrifuged the tubes. This separated the mixture into aqueous, interphase and organic phase.
At what point I should have saved supernatant for protein analysis for ELISA?