H₂O maser luminosities (logarithmic scale, in L_⊙) against the nuclear radio luminosity (logarithmic scale, in erg s^-1 Hz^-1) of maser host galaxies at 6 cm (upper panel) and 20 cm (lower panel). Squares, triangles, and circles represent AGN-masers, star formation-masers, and masers of unknown type, respectively. Pentacles inside squares indicate potential or confirmed disk-maser sources, which are presented in boldface in Table 2. The solid lines show linear fits to the AGN-maser sources.