We also evaluated our xenografts for evidence of EBV infection by ISH or polymerase chain reaction (PCR) for EBV-encoded RNA (EBER1) and found that the human-derived lymphoid tumors were EBER1 positive; however, no signal could be detected in the CD45− xenografts (Fig. 2A,B). Here, PTPRC is linked to Epstein-Barr virus infection.