SMN1 and breast adenocarcinoma: In the present study, we preferentially investigated the effect on the shortening of telomeric repeats and telomerase activity in the human A-549 lung adenocarcinoma, MDA-MB-231 breast adenocarcinoma and U87-MG brain glioblastoma astrocytoma cells treated with 1 μM SMA during prolonged culture time of up to 2 weeks.