Sylvester Stallone's son Sage Stallone found dead

Just a day after Sylvester Stallone made an appearance at Comic-Con 2012 to promote his upcoming movie, "The Expendables 2," the actor's son -- Sage Stallone -- was found dead,  presumably of a drug overdose.

Sage, 36, was found dead in his Los Angeles home on Friday (July 13), reports TMZ, and although the cause of death is not confirmed, a source tells the site Stallone likely overdosed on pills. Authorities are trying to determine if the overdose was intentional or accidental.

PHOTO GALLERY: 2012 celebrity deaths

Stallone's son made his acting debut as a child in his dad's movie "Rocky 5." He went on to act and direct, including the 1996 movie "Daylight." His mother is Stallone ex Sasha Czack.

According to TMZ, Sylvester is "a wreck."

At left: Sage Stallone (left) with uncle Frank Stallone.