Why I could only see knockdown in mRNA level but protein? - help (Jan/17/2008 )

I use siRNA in vitro and in vivo, in vitro study i could observe both knockdown at mRNA and protein level, but in vivo I only could get knockdwon at mRNA level but protein. Can anyone help me to explain this? Thanks a lot.

May be the half life of the protein is different invivo compared to invitro. Give some more time before you analyze the protein levels again.

perhaps there are different isoforms of the protein that you are detecting in vivo.

(Absolutely no experience with siRNA, knockdowns/knockouts etc, but...)

Maybe the mRNA is particularly stable and you're seeing a a bit of carryover.