TERT and cancer: Moreover, the co-existence of BRAFV600E and TERT promoter mutations in papillary thyroid cancer has been shown to have a synergistic effect on poor clinical outcome, probably due to the BRAF-dependent upregulation of several ETS transcription factors, especially ETV1, ETV4 and ETV5, causing telomerase over-expression associated with increased cancer invasiveness and progression (Song et al., 2019a).