Primary human keratinocytes were pre-incubated with NF-κB inhibitor (10 nm, a), extracellular signal-regulated kinases 1/2 (ERK1/2) inhibitor (5 μm, b), p38 inhibitor (5 μm, c), and JNK inhibitor sp600125 (1 μm, d) before stimulation with TNF-α (20 ng ml−1). The gene expression of FLG was examined by real-time RT-PCR. **P<0.01; ***P<0.001. GAPDH, glyceraldehyde-3-phosphate dehydrogenase.