temperature. The filter was probed with polyclonal rabbit anti-
GNA serum (1:10 000 dilution) and goat anti-rabbit IgG horseradish
peroxide conjugate (Bio-Rad) as a secondary antibody (1:10 000
dilution). Incubation and washing procedures were according to
standard protocols (Amersham). Bound secondary antibodies
were detected by enhanced chemiluminescence (ECL) as described
in the manufacturer’s protocols (Amersham).