Study of P21 Expression in Oral Lichen Planus and Oral Squamous Cell Carcinoma by Immunohistochemical Technique.

Statement Of The Problem: Lichen planus is a mucocutaneous disease that is relatively common in middle aged individuals. Some studies have shown that oral lichen planus has a potential to progress to squamous cell carcinoma.p21 is a cyclin-dependent kinase inhibitor that regulates the cell cycle, thus it acts as an inhibitor in cell proliferation.