We also examined whether high m6A methylation applies to RC-L1s, which in humans belong to L1HS, mostly the L1HS-Ta subset (Ta: transcribed subset a).21,73 While the extremely repetitive nature of L1HS precludes their full alignment by short reads sequencing, there are a few that can be detected based on unique-mappable regions in the L1 body and immediate downstream sequences.68 Breast cancer cell line MCF7 harbors one such RC-L1 in the first intron of TTC28 gene in the antisense direction (a.k.a., Chr22-q12.1 L1HS-Ta)68 (Fig. 2e). This evidence concerns the gene TOR1A and breast cancer.