Chu et al. (2017) observed a twofold upregulation of telomerase activity following TERRA knock down. In the zebrafish brain cancer model, sustained telomerase expression in tumor initiating cells not only prevents ALT, but also represses TERRA transcription. These observations establish that TERRA and telomerase play antagonistic roles in TMMs by multiple mechanisms, since the re-expression of tert in brain tumors restores heterochromatin and reduces the expression of TERRA. The gene discussed is TERT; the disease is brain cancer.