H2AX and non-Hodgkin lymphoma: The majority of the chromatin of the control (untreated) lymphoid cells was condensed into irregularly distributed cords or globules that were densely stained by TO‐PRO‐3 and contained sporadic foci of phosphorylated H2AX (γH2AX) or 53BP1 (most pronounced in WSU‐NHL cells), marking DSB and/or ssDNA (Fig. 1A).