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.
'The dust dreams of the world it had once been.
But the dust, alas, does not command the wind.' - Toll the Hounds