What are the reasons that my PCR reaction would fail (no detectable bands on a gel) even if it was successful before?
Some reasons why this may happen: • Using different cell types • Type of antibodies, primers, or reagents used • To resolve the issue of a problematic PCR, make sure you perform a PCR on genomic DNA as positive control in addition to the input and experimental ChIP samples. Remember to use the same components (Taq, buffers, primers, etc) that you use to amplify your ChIP sample. If the genomic DNA sample does not amplify, this indicates PCR failure.
