We examined the expression of Bub1 mRNA and protein in 21 human salivary gland tumors (7 pleomorphic adenomas, 2 warthin tumors, 5 mucoepidermoid carcinomas, 3 adenoid cystic carcinomas and 4 acinic cell carcinomas) and 3 normal submandibular glands using real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR) or western blotting.