Research into LINE-1 (L1) retrotransposons reveals that while ORF1 and ORF2 expression is largely restricted to germ-line and embryonic cells, it occurs specifically in somatic cells like Leydig and vascular endothelial cells. These transposable elements use a "copy and paste" mechanism to move within the genome, and their deregulation is linked to genomic instability and various cancers. For more details, visit Semantic Scholar .