Chromatin immunoprecipitations were performed with cross-linked chromatin from 4 x 106 HaCaT cells treated with Human TGF-β3 #3706 (7ng/ml) for 1 h and either 20 μl of Smad4 Antibody or 2 μl of Normal Rabbit IgG #2729 using SimpleChIP® Enzymatic Chromatin IP Kit (Magnetic Beads) #9003. The enriched DNA was quantified by real-time PCR using SimpleChIP® Human CDKN1A Intron 1 Primers #4669, SimpleChIP® Human ID1 Promoter Primers #5139, and SimpleChIP® Human α Satellite Repeat Primers #4486. The amount of immunoprecipitated DNA in each sample is represented as signal relative to the total amount of input chromatin, which is equivalent to one.