Western blot analysis of PIP protein expression in homozygous B-hPIP mice. Various tissue lysates were collected from wild-type C57BL/6 mice (+/+) and homozygous B-hPIP mice (H/H), and then analyzed by western blot with anti-PIP antibody. 40 μg total proteins were loaded for western blotting analysis. hPIP was detected in salivary gland from homozygous mice but not wild-type mice.

Strain specific analysis of PIP mRNA expression in wild-type C57BL/6 mice and B-hPIP mice by RT-PCR. Salivary gland RNA were isolated from wild-type C57BL/6 mice (+/+) and homozygous B-hPIP mice (H/H), then cDNA libraries were synthesized by reverse transcription, followed by PCR with mouse or human PIP primers. Mouse Pip mRNA were detectable only in wild-type C57BL/6 mice. Human PIP mRNA was detectable only in homozygous B-hPIP mice but not in wild-type mice.