Acute cardiac injury often develops acute kidney injury, called acute cardiorenal syndrome (aCRS), and may later develop kidney fibrosis. Methods: The expression of Ki-67, a marker for entry into cell cycle, was assessed with immunofluorescence (IF). In vivo and in humans, we previously found that CSRP3, a heart-specific protein, is found in plasma soon after cardiac injury. Since abnormal PT-cell cycle in the recovery phase is associated with later kidney fibrosis, we hypothesized that CSRP3 affects PT-cell cycle. CSRP3 may affect cell cycle of PT.