Abstract: Objective To explore the role of MAPK and NF-κB in increase Toll-like receptor 4 ( TLR4 ) expression induced by lipopolysaccharide (LPS ) in pulmonary micro-vascular endothelial cell (PMVEC) in mouse. Methods Isolation and culture mouse PMVEC. PMVEC were exposed to the different concentration LPS at 2h, and 100 μg/L LPS in different time. The concentration of TNF-αin culture supernatant was detected using ELISA. Using PD98059, ERK inhibitor, SB203580, inhibitor for p38 MAPK and PDTC inhibitor for NF-κB pretreated PMVEC. RT-PCR was used to detect the levels of TLR4 and TNF-αmRNA. Western-blot was used to detect the protein expression of nuclear factor-kappa B ( NF-κB ) p65 subunit and ERK / p38 MAPK in nuclear extract after LPS exposure for 6 h respectively. Results At doses of 50~500 ng /mL LPS for 2 h or 100μg / L LPS exposure in different time, the concentration of TNF-αin culture supernatant of PMVEC was increase with both time and dosage dependent ( P <0.01). The levels of TLR4 and TNF-αmRNA in membrane of PMVEC were obviously increase, with the peak at 6h. Above inhibiter decrease the TLR4 and TNF-αmRNA expression separately, and above inhibition effect was increased after simultaneous pretreatment with PD98059 and SB203580. Protein expression of ERK/p38 MAPK and NF-κB in PMVEC induced by LPS were down-regulation by pretreatment with PD98059, SB203580 and PDTC respectively. Conclusion Up-regulation expression of TLR4 in PWVEC of mouse by MAPK and NF-κB pathway induced by LPS.