Re: If the Lizard was the villain in Sam Raimi's Spider-Man 4...
By all accounts, it would have been the Vulture. However, to answer your question, I suppose something would have to push Curt into wanting to research regeneration. Then Curt would have to work alongside some researchers/corporation that would fund the research.
"Sometimes a man must chose. Sometimes the world forces his hand. If a man remains true to himself, and knows what he is, the choice is no choice at all. He must fulfill his destiny and become who he is meant to be.
However much he may hate it."