Mucoepidermoid carcinoma is one of the most common salivary gland malignancies with highly variable biologic potential. Adenoid cystic carcinoma is one of the best recognized salivary gland malignancies with a deceptively benign histological appearance and has the propensity for local invasion and distant metastasis. Cyclooxygenase-2 or prostaglandin endoperoxide synthase-2 (PGES-2)play an important role in angiogenesis, resistance to apoptosis. Matrix metalloproteinase-9 play an important role in remodeling of extracellular matrix under normal physiological situations and overexpression of these enzymes play an important role in tumor invasion and metastasis. Cyclin D1 encodes the regulatory subunit of a holoenzyme that phosphorylates and inactivates retinoblastoma protein and promotes progression through the G1-S phase of the cell cycle. Overexpression of Cyclin D1 plays pivotal roles in the development of cancers. The immunoreactivity expression COX-2, MMP-9, Cyclin D1 proteins was signifying possible roles of these markers in MEC and AdCC salivary gland malignant tumors initiation and progression. ukryj opis