Fig. 6.

Premature expression of a high level of STAT3 reduces PAX6 but does not change responsiveness to LIF. A retrovirus that coexpresses eGFP (A) and wild-type STAT3 (B) was used to infect progenitors in E11.5 cortical explants. C, Four days after infection, STAT3 virus increases the proportion of cells that express the early astrocyte marker S-100β in the absence (−) of LIF but does not cause more cells to respond to LIF as an astrocyte-inducing signal. +, Addition of LIF. The proportion of infected E11.5 cells (D; arrow) that express the neurogenic factor PAX6 (E; arrow) is reduced by STAT3 virus compared with a control virus (F). *p = 0.02; **p = 0.003. GFP, Green fluorescent protein.