Serum HI titers. Mice (8 animals/group) were subcutaneously injected at weeks 0 and 3 with 100 μg docetaxel, inactivated H1N1 influenza virus antigen (equivalent to 10 or 100 ng HA) or inactivated H1N1 influenza virus antigen (equivalent to 10 ng HA) adjuvanted with docetaxel (25, 50, 100 or 200 μg). Blood samples were collected 2 weeks after the second immunization for hemagglutination inhibition test. Values represent geometrical mean titer (GMT) ± S.D. Significant differences with 10 ng HA group was designated as *P < 0.05 and **P < 0.01. N.D. indicates that HI titer was not detectable at the lowest dilution of serum. The solid horizontal line represents an HI titer of 40.