Gene expression is one of the key regulatory processes in modulating accurate and precise responses to a myriad of cellular and environmental stimuli and stress. Promoter proximal pausing and transition to elongation is one of the earliest steps of regulation. The induction and break of promoter proximal pausing and transition to elongation is synchronised by interplay between Positive and Negative transcription elongation factors (PTEFs and NTEFs). Upon a variety of cellular stresses like heat shock and oxidative stress, a blockade is reported in transition to elongation. The exact mechanisms remain unexplored. My PhD project aims to identify the mechanistic role of PTEFs and NTEFs in transcriptional regulation upon stress in the mammalian system.