LMPCR validation. (A) DNA of K562 mass cultures and cell clones containing different numbers of retroviral insertions²⁸  was subjected to insertion site amplification by LMPCR using the conditions described in “Material and methods.” In contrast to the clonal DNA, mass culture DNA does not reveal dominant bands except when cells were propagated for several weeks, revealing a clonal imbalance. (B) Mixing mass culture DNA with increasing amounts of DNA from clone 2.4 reveals that LMPCR recovers dominant bands if these contribute greater than 70% of the population.