According to histopathological evaluation and immunofluorescence staining for PAX5 of the original spontaneous lymphomas, OPL239 was derived from an early-stage DLBCL that still preserved the nodular architecture, whereas OPL241 originated from a more advanced DLBCL, already spread in the spleen (Fig. 5A, upper and middle panels). Here, PAX5 is linked to diffuse large B-cell lymphoma.