NOS3 and hepatocellular carcinoma: It is not known the mechanisms by which the absence of eNOS contributes to the observed differences between male WT and male eNOS-/- C57BL6 mice in response to HCC and post-hypercapnia room-air exposure, but it is tempting to assume that absence of eNOS within the carotid body-carotid sinus nerve complex, and central structures (e.g., retrotrapezoid nucleus) is involved.