The modernist movement in literature was a 'reaction against' traditional literary conventions.
The announcement produced an angry/stunned 'reaction' from most of the people at the meeting.
There has been a 'mixed reaction' [=people have reacted in different ways] to the new policy.
(..) to his disadvantage? I think you should tell the truth. Please don't stand there. Where was he? Mr Lavasani was in the kitchen. He didn't have a reaction to your conversation? If he did I didn't notice. How did you realise she was pregnant? I think she told me. (..)2011 A Separation