XBP1 and cystic fibrosis: Here we provided evidence that XBP1 is a transcription factor of SLC5A1. Furthermore, based on the data shown in Fig. 5 where SGLTi drug Sotagliflozin led to reduced ER stress markers, we expand our hypothesized regulatory axis to a regulatory loop: ER stress → XBP1 → SLC5A1/SGLT1 → ER stress, and speculate that disrupting a node in this loop (i.e., the SGLT1 or the ER stress) breaks this vicious cycle, which may yield benefits to CF cells and ultimately CF individuals.