Clonality of serially transplanted long-term hematopoiesis. Representative LAM-PCR analysis of peripheral blood. Multiple clones contributed to the long-term hematopoiesis of the primary (A), secondary (B), and tertiary recipient mouse (C), and the number of these clones was not reduced by BCNU/O6BG administration. M indicates 100-bp DNA ladder; -c, negative control (5 ng DNA extracted from untransduced C57BL/6J bone marrow cells); and IC, internal control band.