The amino-acid changes in the transcription factor CCAAT/enhancer binding protein-beta (CEBPB, also known as C/EBP-beta) in the stem-lineage of placental mammals changed the way it responds to cyclic AMP/protein kinase A (cAMP/PKA) signalling. The transcription factor CCAAT enhancer-binding protein beta (CEBPB) in acute promyelocytic leukemia cells induced by all-trans retinoic acid. In mouse models, CCAAT enhancer-binding protein beta (CEBPB) is necessary for M2 macrophage-mediated regeneration after muscle injury. In humans, CEBPB expression in blood was strongly associated with muscle strength. Associations between CEBPB expression in blood and muscle strength may be consistent with the CEBPB-dependent muscle repair process.