MSH2 and neoplasm: On the other hand, the HCN:596 patient showed a 100% match among MMR protein expression between primary tumor and PDX, with nuclear staining of all of the proteins (Figure 1—MLH1, MSH2, MSH6, PMS2 lower panels), and aberrant expression of p53, showing intense nuclear staining in the glands of the tumor in the patient and a more heterogeneous pattern in the PDX with a strong diffuse staining pattern in tumor cells (Figure 1, lower panel).