David Luiz has signed a one-year extension at Arsenal, the club announced on Wednesday.
The club also said that Dani Ceballos has extended his deal at the Emirates until the end of the season, while Cedric Soares and Pablo Mari will join the club on a permanent basis.
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"I am really happy that we will have these players in our squad for the future," club technical director Edu said in a statement. "They have been part of the long-term technical plan Mikel and I have developed. They bring the right balance to our squad.
"David is a really important player for us. He has played most of our matches this season and has been important for the team. His passing, his communication with the team on and off the pitch. He helps everyone."
Luis blamed his contract situation for his poor performance in Arsenal's 3-0 defeat at Manchester City. The Brazil international made a mistake for the opening goal and was later sent off after conceding a penalty in an appearance which lasted 25 minutes.
Sources have told ESPN that despite his extension, Ceballos is not expected to sign a permanent deal at the Emirates and will return to Real Madrid at the end of the campaign.
The midfielder has made 26 appearances in all competitions but has failed to score for the club since October.
Sources have told ESPN that Mari will put pen to paper on a four-year contract when the transfer window opens next month, and a fee of £13.5m will be paid to Flamengo in instalments and clauses. However, the club fears that the defender could miss the rest of the season after suffering an ankle injury at the Etihad Stadium.
Cedric will also sign a four-year contract at Arsenal after impressing Arsenal boss Mikel Arteta with his professionalism and positive impact on the dressing room.
"With Pablo we're all disappointed he got injured at Manchester City," Edu added. "Since Mikel arrived here he was asking for a central defender who was left-footed. We were really pleased with Pablo -- his behaviour, the way he is training, his mentality and his quality.
"Unfortunately, he has that injury but of course we are really happy to keep him for the future.
"Cedric is also going to be an important player. He has been unlucky with the injuries but he is close to being ready and gives us more strength in the right-back position. We're also pleased Dani will finish the season here. He is making a good contribution and we look forward to him having a strong finish to the season."
Arsenal face Cedric's former club Southampton on Thursday after losing their both Premier League matches after the restart.
Information from ESPN correspondent James Olley was included in this report.