Figure 4.

S1P₁ is highly expressed on LSEC and does not change after arsenic exposure. A: Liver sections from control mice and mice exposed for 2 weeks to 100 μg/L of arsenic were immunostained for S1P₁ (green channel), PECAM (red channel), and nuclei (blue channel). CV and PV designate a central and portal vein lumen respectively. B: Total liver RNA extracts from the same mice, as well as RNA extracts from purified LSECs, were assayed by RT-PCR for S1P₁, S1P₃, or HPRT transcripts, as described in Materials and Methods. C: Total liver protein extracts from control or arsenic exposed mice, as well as control and ex vivo arsenic-exposed LSECs, were immunoblotted for S1P₁ and β-actin. Ex vivo 2.5 μmol/L arsenic exposures lasted 24 hours. All lanes represent proteins from separate liver or cell extracts.