Interestingly, in this work we documented that the expression of one of the most important mucins of the lung, Muc5b, could be regulated with the IL1β pathway through the transcription factor CREB, indicating a strong association of this transcription factor with Muc5b promoter in COPD animals infected with Pneumocystis compared with the other experimental groups. This evidence concerns the gene CREB1 and chronic obstructive pulmonary disease.