However, consistent with flow cytometric analysis of marrow isolated from SUM159-inoculated mice (Fig. 2f–h), we detected tumor cells by qPCR analysis for human B2M expression in 2/8 (25%) mice and human HPRT1 in 3/8 (38%) mice (Fig. 5e and Supplementary Fig. 6). The gene discussed is HPRT1; the disease is neoplasm.