In renal transplant patients, Sigdel et al. observed that acute rejection and BK-virus-associated nephropathy, two main causes of acute loss of renal function in this population, present with different urinary exosomal protein expression profiles; higher abundance of CLCA1, PROS1, KIAA0753, and ApoM was linked to acute rejection [64]. Here, CLCA1 is linked to kidney disorder.