In agreement, our previous work indicates that a SINE-B1 retrotransposon exerted an insulator effect to downregulate gene expression in mouse hepatocarcinoma cells [32, 35, 42], whereas transcription of the X45S Alu element was needed to repress Nanog in differentiated human teratocarcinoma NTERA cells [17]. Here, NANOG is linked to teratocarcinoma.