SLC5A3 and idiopathic pulmonary fibrosis: Compared to normal lung tissues, expression of a Na+-coupled inositol transporter, SMIT1 (SLC5A3), was ubiquitously upregulated in all IPF lung tissues from all stages of IPF, while only a slight decrease of the proton coupled inositol transporter HMIT (SLC2A13) was seen in lung tissues from end-stage IPF (Additional file 1: Fig. S2A).