ChIP Protocol Chromatin Immunoprecipitation (ChIP) assay is an important method for transcriptional regulation monitoring with uncovered knowledge of interactions between specific proteins and a genomic DNA region. Given the fact that DNA-binding proteins (including transcription factors and histones) in living cells can be cross-linked to the DNA that they are binding, ChIP is used to immunoprecipitate the protein–DNA complex out of cellular lysates by an appropriate antibody. The immunoprecipitated complexes are collected by centrifugation, and proteins are eluted for further analysis such as western blot and LC/MS. Nucleic acid analysis is achieved through PCR, RT-PCR, cDNA sequencing and microarray. This protocol provides a detailed procedure to achieve successful ChIP assay in a fast and efficient manner.