MKI67 and Patent ductus arteriosus: Finally, to correlate these in vivo data with previously shown information of SLIT2 impact on the proliferation rate of Schwann cells, we analyzed the proliferation rate of Schwann cells in vivo. We revealed that nerves with Ki67-positive Schwann cells in mouse PDA tumors with a high level of SLIT2 (αSMA+/SLIT2+) are significantly increased compared with nerves present in mouse PDA with a low level of SLIT2 (αSMA−/SLIT2−) (Figure 6d).