After you get sunburned, your skin temporarily stops making tan pigment because a protein called ATM redirects another protein (MITF) to fix DNA damage instead of making color.

After sun exposure, a chemical tag (phosphate) is added to a protein called MITF, making it stop making pigment and instead team up with other proteins to fix DNA damage.

If you block the ATM protein in skin, the skin tans more after sun exposure because it can’t pause pigment production to fix DNA damage.

When skin cells are hit by UVB light, they can die and send out inflammation signals — but this happens even if their DNA damage repair system is broken, so that system isn't needed for this response.

Large DNA deletions in skin that never gets sunburned are linked to past sun exposure—likely because UV light breaks DNA strands, and the cell’s repair job often messes up, deleting big chunks.