“…A few clinical results indeed indicated that nm23 expression, as anticipated from the in vitro investigations, correlated with better prognosis (Bevilacqua et al, 1989;Barnes et al, 1991;Hirayama et al, 1991;Nakayama et al, 1992;Campo et al, 1994;Hsu et al, 1999). Results from other studies, on the contrary, suggested that nm23 might facilitate tumour development and disease progression (Hailat et al, 1991;Zou et al, 1993;Müller et al, 1998;Pavelic et al, 2000). The discrepancy may be due to, in part, the difference of study design and, in part, study end point selected.…”