To investigate whether SETD2 and H3K36me3 deficiency impair the activation of HR repair in advanced‐phase CML, LAMA84 (SETD2/H3K36me3‐proficient) cells before and after SETD2 silencing (Figure 3SB) and KCL22 (SETD2/H3K36me3‐deficient) cells before and after SETD2 transfection (Figure 3SC,D) were studied by immunofluorescence to assess phosphorylated H2AX (a DNA double‐strand break [DSB] marker) and Rad51 (a marker of ongoing HR) foci in steady‐state conditions and after hydrogen peroxide (H2O2) exposure (1 mM for 60 min) or chronic UV exposure. Here, SETD2 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.