Strain specific LIF expression analysis in homozygous B-hLIF mice by ELISA. Bone marrow cells were collected from wild-type C57BL/6 mice (+/+) and homozygous B-hLIF mice (H/H) and stimulated with LPS in vitro, and the cell culture supernatant after stimulation was analyzed by ELISA with species-specific LIF ELISA kit. Mouse LIF was detectable in wild-type mice. Human LIF was exclusively detectable in homozygous B-hLIF but not wild-type mice.