DNA seq of rasH2 mice
Thirteen amplicons were synthesized individually by PCR, using 500 ng of HindIII digested mouse genomic DNA as template. The forward and reverse primers for each target were synthesized with 9-base UMI sequences at their 5-ends. PCR products were quantified, diluted and quantified. Libraries were prepared using 10 ng of each DNA mixture for DNA end-repair, 3 end adenylation and ligation of index/adapter sequences as described in the Illumina TruSeq ChIP Sample Preparation Kit. DNA was purified on agarose gel and recovered using the MinElute PCR Purification Kit. DNAs were serially diluted and quantified by digital droplet PCR (ddPCR) using the ddPCR Library Quantification Kit for Illumina (BioRad, Hercules, CA) and the QX200 Droplet Digital PCR System (Bio-Rad).  Based on ddPCR quantification, a volume of DNA containing 1.95 x 107 total molecules was used in the final PCR step of the Illumina TruSeq ChIP library preparation (based on the planned use of 1.5 x 106 molecules of each amplicon x 13 amplicons).