MUC5B and atrial fibrillation: AF dose‐dependently induced MUC5AC expression. Increase occurred as early as 6 h after treatment. MUC5B also dose‐dependently increased but less than MUC5ACAF‐induced mucin expression repressed by EGFR tyrosine kinase inhibitors, EGFR blocking antibody, and serine protease inhibitors. PAR2 neutralising antibody did not block mucin gene expressionAF‐induced expression of MUC5AC and MUC5B in ECs independent of PAR2. EGFR activity was required, but not sufficient, to induce mucins. Mucins induced by activation of ERK pathway. Blocking Ca2+ but not ROS prevented mucin induction