NFL players take to Twitter to congratulate Rob Gronkowski after retirement announcement Unknown 00:15 The 29-year-old tight end announced his retirement Sunday on Instagram. Share this Share on FacebookTweet on TwitterPlus on Google+ Related PostsEugenie Bouchard's locker room fall at US Open 2015 'mostly' USTA's fault, finds New York juryWinter Olympics 2018: Teen Alina Zagitova pips compatriot Evgenia Medvedeva to win 1st gold for OAR at PyeongchangI-League: AIFF changes dates of matches involving title contenders Minerva Punjab FC, East Bengal and NEROCA FCVillarreal defender Ruben Semedo charged with attempted murder and kidnappingHighlights, Sevilla vs Manchester United, Champions League R-16 1st leg: United hold Sevilla to goalless drawOpen 13: Stan Wawrinka retires in second round after knee flares up; Nicolas Mahut upsets Gilles Muller