Arsenal defender Shkodran Mustafi has joined Schalke on loan until the end of the season.
The German defender follows a number of departures from the Emirates during the winter transfer window.
After the announcement, Gunners boss Mikel Arteta said: "Musti has been a key player for us for a long period of time.
'He played a very important part in my first season as manager and I'd like to thank him for his professionalism and for always being ready when called upon.
"Everybody at Arsenal wishes Musti well at Schalke."