Madonna and Sean Penn Reunite, Party With Lindsay Lohan—See the Pics

Actor steps out in support of his ex-wife's latest project in New York City

Their marriage may have ended years ago, but Madonna and Sean Penn have clearly remained on good terms.

A perfect example of that was on full display on Tuesday night when the Material Girl's ex-husband attended a screening party for the singer's SecretProjectRevolution film project at the Gagosian Gallery in Manhattan.

A source at the event tells E! News that Penn arrived early and stayed almost until the end of the shindig, adding that the Oscar winner was really supportive and rather flirty with Madonna all night.

Donna Karan, Anderson Cooper, Calvin Klein, Zachary Quinto, Charlotte Ronson, Zac Posen were among the famous faces who were on hand.

Also in attendance?

Lindsay Lohan, who was spotted taking pictures with everyone and having a great time.

Source adds that the night ended with Madonna's dancers in the middle of the floor and Lohan was right there cheering them on.

—Reporting by Alicia Quarles