To pinpoint how ERK1/2, JNK, and P38 are involved in CPS- or M. ovipneumoniae-induced apoptosis in ALI cultures of sheep bronchial epithelial cells, we further investigated impacts of U0126 (an ERK1/2 inhibitor), SP600125 (a JNK inhibitor), and SB203580 (a P38 inhibitor) on MAPK signaling in sheep bronchial epithelial cells in response to CPS stimulation or bacterial infection. This evidence concerns the gene CAD and bacterial infectious disease.