The Gurdon and Yamanaka experiment demonstrated:
John Gurdon's nuclear transfer experiments in Xenopus and Yamanaka's transcription factor reprogramming collectively proved that differentiation does not entail irreversible genetic alteration or loss of genomic information. Gurdon demonstrated that intestinal nucleus could support cloned tadpoles developing to adult frogs, while Yamanaka showed differentiated fibroblasts return to pluripotency with defined factors alone. Both experiments established epigenetic plasticity as central to development and reversed Waddington landscape conceptually. Recognition transformed concepts of cell fate reversibility, culminating in Nobel Prize 2012, and enabled patient-specific induced pluripotent stem cells.
Ref: Gurdon 1962, Yamanaka 2006, Nobel 2012; Gilbert, Chapter 6: Reversibility of differentiation and pluripotency induction.