In order to understand the role of CYP1B1 and of its common polymorphism V432L, we characterised head-and-neck squamous cell carcinoma (HNSCC) cell lines that do not express this cytochrome, and we generated isogenic derivatives of these lines expressing similar levels of the two variant forms of CYP1B1. The gene discussed is CYP1B1; the disease is head and neck squamous cell carcinoma.