The baseline urinary protein excretion of BWF1 mice was measured at 20 weeks of age, and the mice were assigned to either the α-GalCer group (n = 8), which was intraperitoneally injected with 2 μg/body of α-GalCer (Funakoshi, Tokyo, Japan) once a week for 4 weeks from 24 weeks of age, or the vehicle group (n = 10). The baseline urinary protein excretion was balanced between the two groups and amounted to less than 1 mg/day. The urinary protein excretion was thereafter measured periodically, and was considered to be positive when greater than 1 mg/day.