PRRT2 and actinic keratosis: Indeed, only one PKC-targeted drug has been approved until now: the C1 domain-binding PKC activator ingenol mebutate was approved for the treatment of actinic keratosis, precursor of squamous cell carcinoma in 2012, but has recently been withdrawn from the market due to risk of skin cancer (Freiberger et al., 2015; European Medicines Agency, 2020).