Figure 4.

γ-H2AX ChIP-seq in UNG^+/+ and UNG^−/− cells. Cells were treated with IC₅₀-level pemetrexed (UNG^+/+, 200 nM and UNG^−/−, 25 nM) or with 20 μM cisplatin for 24 h and subsequently processed for ChIP-seq as described in the Materials and Methods section. Cisplatin was utilized as a control DNA-damaging agent that forms DNA double-strand breaks. (a–c) Venn diagrams of the ChIP-seq peaks generated comparing signal overlap for pemetrexed treated UNG^+/+ and UNG^−/− cells (a); pemetrexed treated and cisplatin treated UNG^+/+ cells (b) and pemetrexed-treated and cisplatin-treated UNG^−/− cells (c). (d) Midpoint coordinates for each γ-H2AX peak were used to obtained signals ±1 kb for the coordinate (within a 25-bp window). The average signal in each window for each peak shown for UNG^+/+ pemetrexed treated (top left); UNG^+/+ cisplatin-treated (top right); UNG^−/− pemetrexed-treated (bottom left) and UNG^−/− cisplatin-treated cells (bottom right)