ESPL1 and lymphoma: To ascertain that Separase was localized to the nuclei of non-mitotic (interphase) cells in the lymphomas derived from the ESPL1+/hyp, p53−/− mice, co-staining was performed with Separase antibody and a anti-Phospho Histone H3 (Ser 10) antibody as a mitotic marker (Figure 5B, bottom panel).