LCN2 and acute kidney injury: AKI induces a rapid and massive upregulation of NGAL mRNA within the thick ascending limb of Henle's loop and in the collecting ducts, originating the so-called “NGAL renal pool” [101]; the accumulation of NGAL in the distal nephron leads to a significant increase in urine NGAL (uNGAL), which represents the major fraction of kidney tissue-derived NGAL.