Last November, a former guard at the Wexner Center for the Arts in Ohio entered the Center shortly after it opened, shooting and spray painting artworks before killing himself. Rachel Harrison’s sculpture ‘Valid Like Salad,’ which features a portrait of Al Pacino in Scarface and indirectly questions who we validate as heroes, was one of the targeted artworks. Now on display at Greene Naftali Gallery, it is a chilling witness to our current epidemic of gun violence. (In Chelsea through June 18th).