MUC5B and lung carcinoma: Conservatively to human data (2, 3, 20), canine lung epithelial cells spread into alveolar type 2 cells (overexpressing genes of surfactant proteins and napsin A protein, the latter being used as a lung carcinoma marker in dogs), alveolar type 1 cells (expressing AGER), secretory cells (expressing SCGB1A1, MUC5B), basal cells (expressing KRT14 and transcription factor TP63) and ciliated cells (expressing CAPS, FOXJ1, CCDC78, HYDIN).