Quality control: H2A.X links to better iPSCs.

Incorporating induced pluripotent stem cell (iPSC) technology in regenerative medicine requires better methods for defining and obtaining high-quality lines. Two papers in this issue of Cell Stem Cell (Buganim et al., 2014; Wu et al., 2014) now show that H2A.X deposition can serve as a functional epigenetic marker for distinguishing the quality of iPSCs, thus providing insights for better reprogramming methods.