The effects of EGF, KGF, and Y-27632 on the colony formation of human limbal epithelial cells. (A): Rhodamine B-stained 100-mm dish. (B): Relative CFE; n = 7. **, p < .01. CFE was normalized as CFE of EGF = 1. (C): Phase contrast micrograph of colonies at day 7. (D): Immunostaining of colonies at day 10 using anti-p63 antibody (green). Scale bars = 100 μm (C, D). Abbreviations: CFE, colony forming efficiency; E+Y, epidermal growth factor and Y-27632; EGF, epidermal growth factor; K+Y, keratinocyte growth factor and Y-27632; KGF, keratinocyte growth factor.