In May, just three days prior to announcing his split from Heard
, Depp's mother died after battling a long illness
. She was 81. "The contributions Johnny has continually made in honor of his mother have been instrumental in helping us to develop the kind of research we need to move the needle forward in the fight against lung cancer," Dr. Mirhadi said, adding that Depp has made "regular visits" with cancer patients, and has been "instrumental in supporting research on lung cancer in our department at Cedars-Sinai."