My most sincere gratitude is extended to my supervisor, Richard Sharpe, who not only imparted his wisdom of Science, but also his inspiring enthusiasm at each stage of my PhD. I could not have asked for a more patient, supportive and caring supervisor. You always said Friday was the 'day for results' and that certainly rang true on several Fridays, be it good or bad. Regardless of the outcome, you were always there to listen, advise and discuss.A big thank you to my second supervisor, Lee Smith, for his thought-provoking and helpful input throughout my PhD and for the critical assessment of this thesis.Thank you to the Sharpe group, both present and past members, in particular Marion Walker, Chris McKinnell, Sheila Macpherson, Sander van den Driesche, Afshan Dean, Tom Chambers and Rod Mitchell. Thank you especially to Chris and Sheila for their invaluable help, to Tom for his assistance with ChIP, and to Laura O'Hara for the use of her mouse model. Thank you all for teaching me essential lab techniques, and answering all of my questions, without which, this thesis would never have existed.A big thank you to those who started out as work colleagues, but have now become close friends. To Fiona, from learning about Spirogyra many moons ago to the present! To Lorraine, for the numerous fun-filled nights out and for her daily phone calls to keep me going! To Afshan, for always organising a well needed night out! To my 'office buddies', Doug and Fiona, for always having time to assist with anything I ever needed. Thank you for lending an ear and making me laugh; be it over a coffee or a few beers.Thank you to the girls back home, for always checking in on me and making sure there was always a weekend planned to look forward to, especially Caitriona, Sile, Helena, Edwenia, Therese, and Rebecca. I cannot thank Andrew enough for his unwavering support, patience and motivation. Thank you for never once doubting my capability, even at those times when I did. And of course, for casting an analytical eye over this thesis at the end. Thank you for being there for me. Oh and I know it's my turn to cook... Finally and most importantly, thank you to my family; Mam, Dad, Lorna, Cora, AG, John and the new arrivals! Thank you for your support and encouragement every single day, so that home never felt too far away. "Furthermore" thank you to Cora for taking the time to read over this thesis! Thank you to my parents for providing me with everything I have ever needed; support, love and laughter. Without you, none of this would have been possible. Sin é, Buíochas le Dia.