sentence: In the presence of the host factor , HIV-1 IN produced a distinct ladder of products that migrated above the nicked form of the target DNA ( Figure 3B , compare lanes 1 , 6 and 17 ) , as expected for products of single and multiple half-site integration events.Reactions containing EIAV IN and the 120 bp EIAV RU5 substrate revealed a major product band migrating as a ∼ 3200 bp linear DNA fragment ( Figure 3B , lanes 13 – 16 ) .