GDNF and nasopharyngeal carcinoma: Real-time PCR revealed marked induction (26 ± 3-fold) of Gro1 mRNA levels in IL-1β-treated NPC compared to untreated controls (t(4) = 53.9, p < 0.0001), while growth factors for neuronal progenitors, including GDNF and FGF2, were not significantly induced (Fig. 2a).