H2AX and acute kidney injury: Double immunofluorescence assays and western blot analysis indicated that cisplatin treatment induced the expression of gamma histone variant (γ-H2AX), a strong marker of DNA double-strand breaks (DSBs) as an early response to DNA damage in cisplatin-induced AKI.19 The expression of γ-H2AX was further increased by in vivo CDK12 knockdown after cisplatin treatment (Fig. 4A).