TWIST1 and breast cancer: LARP7 is expressed at low levels in invasive breast cancer tissues and cells; therefore, when a reduction in LARP7 expression is observed, P-TEFb (positive transcriptional elongation factor b) in 7SK snRNP is released, and P-TEFb is reassigned to the transcriptionally active super elongation complex, allowing P-TEFb activation and EMT transcription factors (including FOXC2, Slug Twist1 and ZEB2) to be transcriptionally increased, which ultimately promotes breast cancer invasion, metastasis and EMT (60).