“…Although there are several reports concerning the effects of oxidative stress induced by heavy metals and its role in glutathionylation and carbonylation processes in tissues of mussels (Kirchin et al, 1992;Fagotti et al, 1996;Dalle-Donne et al, 2003a;Dalle-Donne et al, 2003b;Gomez-Mendikute and Cajaraville, 2003;McDonagh et al, 2005), the involvement of signal cascades in the induction of these processes in haemocytes of Mytilus after exposure to heavy metals still remains unclear. Cd has been reported to induce signal transduction cascades, such as protein kinase C (PKC), tyrosine kinase and casein kinase II (Adams et al, 2002), and recent studies in our laboratory have shown the induction of a PKC-mediated signal transduction pathway with a concomitant increase of ROS production and Na + /H + exchanger (NHE) stimulation in Cd-treated cells of mussels (Dailianis and Kaloyianni, 2004 expressed integral membrane protein involved in the coupled exchange of Na + with H + in a variety of eukaryotic cells, is considered of vital importance, since it has been suggested to play important roles in cytoskeletal reorganization, cell migration (Reshkin et al, 2000;McHardy et al, 2004;Paradiso et al, 2004;Konstantinidis et al, 2009), regulation of intracellular pH (pH i ) (Moolenaar et al, 1983;Bianchini and Pouyssegur, 1994), cell volume control (Cala, 1983a;Cala, 1983b) and other cell activities such as cell adhesion, proliferation and apoptosis (Tominaga and Barber, 1998;Khaled et al, 2001;Moor et al, 2001;Avkiran and Haworth, 2003;Orlowski and Grinstein, 2004;Koliakos et al, 2008).…”