NBC says it's adding four new dramas to its 2009-2010 schedule, including a pair of medical shows and one from filmmaker Howard, the series "Parenthood." The series is based on the 1989 movie directed by Howard and stars Peter Krause and Maura Tierney.

NBC also announced two new comedies, including one with Chevy Chase, and prime-time "Weekend Update" shows.

The network says it's renewing "Heroes," "Parks & Recreation" and the police drama "Southland." More renewals may be announced later this month.

Leno, who leaves the "Tonight" show this month, will star in a nightly prime-time series this fall.