Relative retrieval frequency of sequencing reads of integration sites in in vitro and in vivo samples. Retrieval frequency of sequencing reads corresponding to a unique LV integration site from the in vitro culture and the indicated organs of mice that received a transplant with CD34⁺ HSPCs derived from BM (A), MPB (B), and CB (C) cells. Within a red box are represented the integrations at CISs (considered only CISs constituted by ≥ 4 integrations). LAM-PCR products were sequenced by 454-pyrosequencing or Sanger chemistry. Each bar shows the percentage of reads for each integration site in the sample dataset. The total number of reads and of unique integration sites (INTS) in each sample dataset is given. Integrations represented by < 2% of the total reads in the dataset were pooled and shown in black at the top of each bar (< 2%). Integrations represented by > 2% of the total sequencing reads are shown individually with the symbol of the targeted gene. Identical integrations found in different organs of the same mouse are shown in green. (D) The averaged percentage of sequencing reads representing CIS integrations and non-CIS integrations was not statistically different.