Research interestRetrotransposition is a common molecular mechanism of all eukaryotes. It has largely contributed to the modelling and evolution of all genomes. In human, LINE-1 (Long Interspersed Nucleotidic Element-1 or L1) retrotransposons represent about 17% of the genome. It is the only autonomous mobile element that remains active, and is responsible for the amplification of non-autonomous retrotransposons such as Alu sequences and retropseudogenes. Thus, during evolution, L1 has contributed to almost one third of the human genome.In the last decade, our work has contributed to determine the impact of L1 mobility on genomic instability and variability (Morrish, Gilbert et al. 2002, Gilbert et al. 2002, 2005). We also elucidated the basal retrotransposition complex (Doucet et al. 2010). Furthermore, we demonstrated the multiple steps by which L1 can recruit cellular RNAs for their amplifications, contributing again to genomic variability (Garcia-Perez et al. 2007, Doucet et al. 2015).