DNA damage accumulation and consequent DNA damage response activation may be the result of a variety of DNA insults and may contribute to the phenotypes associated with aging and cancer initiation. One of the most robust markers of the generation of a DNA double strand break and DNA damage response activation is the phosphorylation of the histone H2AX on serine 139. The modified form (also known as γH2AX) labels the sites of DNA damage by spreading for megabases of chromatinised DNA. Its detection is therefore a reliable readout of the cellular events associated with DNA damage generation.
We describe here a detailed protocol for the reliable detection of γH2AX in mammalian (mouse or human) formalin-fixed paraffin embedded tissues.