GREY'S ANATOMY - "Now or Never" - Dr. Derek Shepherd works on critical patient "John Doe" as Drs. Grey, Torres and Hunt assist, on "Grey's Anatomy," THURSDAY, MAY 14 (9:00-11:00 p.m., ET) on the ABC Television Network. ELLEN POMPEO, PATRICK DEMPSEY, T.R. KNIGHT, SARA RAMIREZ, KEVIN MCKIDD