NRF1 and hydrops fetalis: Specificities for PRAT were further enlightened for three upstream candidates that were over-expressed in HF pigs, without any significant variations in their expression levels compared with LF pigs in SCAT: RXRG involved in mediating the anti-proliferative effects of retinoic acid, the nuclear respiratory factor NRF1 involved in cell response to stress, and the myocyte enhancer factor MEF2A involved in innate immune response.