a, Mouse fibroblasts were cultured on microgrooved or flat surfaces in the absence or presence of VPA or TCP for 3 days, followed by Western blotting analysis of histone modifications AcH3, H3K4me2, and H3K4me3. Total histone H3, GAPDH and Actin are shown as loading controls. b, Confocal microscopy shows the fluorescence intensity of histone modifications localized in the nucleus (scale bar, 10 μm). c, ChIP-qPCR analysis shows fold enrichment of histone modifications at the promoter regions of Oct4, Sox2, and Nanog (n=3). d, Reprogramming efficiency of fibroblasts transduced with OSKM in the presence of chemical compounds, VPA and TCP (n=5). * p<0.05 (two-tailed, unpaired t-test) compared with the control flat surface.