Below are just a few of the San Francisco 49ers players' reactions on Twitter and Instagram to the Justin Smith retirement announcement.

QB Colin Kaepernick

It's been a pleasure Cowboy!

A photo posted by colin kaepernick (@kaepernick7) on

S Eric Reid

NT Ian Williams

Learned so much from these dudes that I couldn't explain it in words. I came in almost 5 years ago now. I was blessed to learn and watch one of the best defenses to ever play this game... The type of players I had the privilege to watch @patricklwillis @navorro_bowman @aldonsmith #ahmadbrooks #parysharelson #dashongoldson @dontehitner31 #carlosrogers @illest972 #rickyjean #justinsmith @raymcd91 #issacsopoaga I saw what greatness really was from this group of guys... And we had some dogs on offense too... With JSmith retiring today I wish him and his family the best in the next chapter of their lives. But I know he can't/won't stay far from this team and this fan base. All the best to @patricklwillis #chrisborland and #justinsmith 👌👌👌👌 #respect

A photo posted by Ian Williams (@iwilliams93) on

And of course Williams' response to a fan asking, "some 'Niners fans' panicking after the JSmiths announcement...what do u have to say?"

And of course there are former 49ers teammates that also went to social media to share their thoughts.

LB Dan Skuta, Jacksonville Jaguars

LB Darius Fleming, New England Patriots

OL Jason Slowey

RB Anthony Dixon, Buffalo Bills