How have the courts interpreted the prison mailbox rule in relation to federal filing dates?

^3. Unless otherwise noted, petitioner's filing dates referenced herein are based on the prison mailbox rule, pursuant to which a document is deemed served or filed on the date a prisoner signs the document (or signs the proof of service, if later) and gives it to prison officials for mailing. See Houston v. Lack, 487 U.S. 266 (1988) (establishing prison mailbox rule); Campbell v. Henry, 614 F.3d 1056, 1059 (9th Cir. 2010) (applying the mailbox rule to both state and federal filings by prisoners).