The tough guy actor got all choked up while talking about his film Silver Linings Playbook. Katie asked him if he felt a greater responsibility doing a project that director David O. Russell -- whose bi-polar son inspired Bradley Cooper's character -- was "personally invested in." "Of course, I understand," De Niro replied. After a long pause, he tried to continue, but then he began to break down. He continued, "I don’t like to get emotional, but I know exactly what he goes through."

De Niro's father was believed to be bipolar and suffered from bouts of depression. 

SOURCE: NY Post