There are many different cutaneous malignancies, but malignant melanoma, squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) represent approximately 98% of all skin cancers.In literature, these three skin cancers are often divided into melanoma and nonmelanoma skin cancers (NMSC; including BCC and SCC). However NMSC can be considered a misnomer, as there are many other rare cutaneous malignancies that are not a melanoma. A more appropriate term to classify BCC and SCC together could be keratinocyte carcinoma (KC) as they both arise from keratinocytes. Melanoma is the least common (about 11% of all skin cancers) but one of the most deadly types of skin cancer and develops from melanocytes. BCC is the most common skin cancer (approximately 70% of all skin cancers) and also the least dangerous of the three. However, substantial morbidity and cosmetic disfigurement can occur (figure 1), because around 80% of the BCCs are located within the chronically to the sun-exposed head and neck region. The studies presented in this thesis primarily focus on BCC.