POSTN and kidney disorder: In addition, cells in sub-cluster 0 have few specific genes, including POSTN and CXCL12. Postn (periostin) is expressed in the cortical stroma of the newborn rat kidney (Ito et al., 2002), in the mouse it is expressed in the renal stroma and the ureteric mesenchyme (Sorocos et al., 2011), and is a key player in the progression of renal disease, mediating inflammation and fibrosis (Prakoura and Chatziantoniou, 2017).