Expression of serine racemase mRNA in activated microglia. Semi-quantitative RT-PCR was performed to detect mRNA for serine racemase and GAPDH in microglial cultures incubated 20 h in the absence (Con) or presence of proinflammatory stimuli. A. Primary microglia treated with 15 μM Aβ1–42. [Densitometric analysis of racemase/GAPDH: Con: 5.12 ± 0.64; Aβ: 9.78 ± 0.3 (p 0.005)] B. HAPI microglial cell line treated with 15 μM Aβ1–42. C. N9 microglial cell line treated with 300 ng/mL LPS or 10 nM sAPPα695.