Having been through a few acquisitions, I have learned the truth of this. Eventually, I learned that if a company I work for announces they're being acquired, the best course of action for me is to start looking for other opportunities.

Even if I'm not laid off (which I haven't been yet in these situations), I'm effectively being hired by a new company that I haven't vetted. It's the perfect opportunity to reassess to determine if I fit into the new company and to scout around for something I may fit better in.