Erik Per Sullivan, who played Dewey on 'Malcolm in the Middle,' will not be returning for the revival series. Bryan Cranston says he is going to Harvard.

"He's really, really smart, and he's getting his master's at Harvard right now. He said, 'Oh God, no, I haven't acted since I was 9 or something. So I'm not into it.' "Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer​​,

Sullivan is the only member of the core cast who's not returning for the reboot of the beloved family sitcom. Bryan Cranston was thrilled to reunite with his Malcolm in the Middle family for a revival series after nearly two decades off the air.