 It is thought that when keratinocytes have been damaged by UVB radiation, this triggers a series of processes, caused in part by damage to the DNA.A study indicates that it may be at the mitochondria where the various processes (ligan-dependent receptor activation and cytosolic signaling) pathways are activated by the production of reactive oxygen species (ROS) that may direct the destruction of keratinocytes through apoptosis by activating caspase.As a result of increased exposure to an oxygen-reduced environment, this promotes the development of ROS thereby linking the incidence of ROS with keratinocytes and making these cells more sensitive to UVB radiation.