Longtime Pittsburgh Steelers linebacker James Harrison announced on Monday that he is retiring from the NFL. Harrison made the announcement via his Instagram account. "I've missed way too much for way too long...and I'm done. Many thanks to my family, coaches, the fans, and everyone who played a role in my football life," he wrote in a caption. Harrison played 15 NFL seasons, 14 of them with Pittsburgh. He recorded 84.5 sacks throughout his career, and for a time was one of the most dominant pass-rushers in the NFL. From 2007 through 2011, Harrison, who had 54 quarterback takedowns during that stretch.