XBP1 and atrial fibrillation: Finally, upstream regulators predicted to explain the distinct proteome displayed by AF+ cells included transcription factors involved in the regulation of cell cycle, senescence and apoptosis (TP53, MYC, CDKN2A), ER stress and unfolded protein response (XBP1), autophagy and lysosomal biogenesis (TFEB) and inflammatory responses (NFKBIA, PPARA) (Figure 5E and Figure 5—source data 3).