Secondary cell reprogramming systems: as years go by.

The groundbreaking discovery of the induced pluripotent stem cells in 2006 brought a major paradigm shift in our understanding of the plasticity of differentiated cells. An unprecedented effort has been invested to elucidate the underpinning molecular mechanisms of the dramatic changes in cell properties, using the powerful secondary reprogramming systems (2°RS). This review outlines the key components of the 2°RS, its recent development and applications that have led to a deeper understanding of the 'magic' of induced cell fate changes.