Evidence of another P-gp-CNTF-independent-regulation pathway. a) Addition of IFNγ at 300 U/ml in the culture medium induces an increase of the P-gp cellular level (+48.42% ± 30). This increase remains unchanged by the addition of the hLIF05, partial LIF receptor inhibitor at two concentrations (+69% ± 35 at 0.5 μg/ml and +76% ± 30 at 5 μg/ml). b) The same effect is observed in CNTF-deficient astrocyte culture. Addition of IFNγ at the same concentration induces a major significant increase of P-gp cellular level (+252% ± 68, factorial ANOVA significant at 95%, t-test p < 0.01**).