To this end, we generated MDA-MB-231 breast cancer cells, negative for ERα and stably expressing GFP-ERα fusion protein, to use as an alternative model to MCF7 cells and as a fast model to screen the optimal irradiation condition to test then in L-ChIP assay (Supplementary Fig. S4 and Materials and Methods). The gene discussed is ESR1; the disease is breast carcinoma.