strange expression model - (Jun/02/2005 )

one of the shorter protein i am expressing now was induced strangely. after two hours induction with IPTG i can see a quite strong band of expression, strangely after 4 hours induction the band become faint and even can not see it expressed. Does anyone have the same situation? really interesting. What is the protein going to ?

Anyone has faced the same situation? just wondered? what is the possible reason?
Thanks million

I've never seen it, but could it be degradation? Or maybe aggregate into bigger molecules and shifted on the gel. Just guessing