To evaluate the effect of PRMT5 inhibition on DNA damage, an imaging assay was used to assess levels of DNA damage (phosphorylated histone H2AX, γH2AX) in three ovarian and one breast cancer cell line treated with a dose response of the clinical PRMT5 inhibitor, GSK3326595 (referred to as PRMT5i). Here, PRMT5 is linked to breast carcinoma.