Perhaps best remembered as John Travolta's troubled friend Bobby in Saturday Night Fever, and as a high school geek who helps Kathleen Turner time-travel (from the 1950's back to the 1980's) in Peggy Sue Got Married.
Worked with two of the most famous Italian directors, Martin Scorsese and Francis Ford Coppola, both in the 1980's and within a few years from each other.