Sometimes you hear people say "we're like a startup inside of a big company." This is a great example of why it's hard to make that work. In a big company, you have one source of funding, and they can pull the plug at any moment--sometimes because your project is doing badly, and sometimes just because you don't fit into the overall corporate strategy this year. At a startup, you only die if you run out of money (which doesn't happen overnight), and if an existing investor says no, you can still raise capital on the open market.
