Figure 1: Inducible expression of sFRP1 in corneal stroma. (a) Diagram showing the generation of bitransgenic mouse strain keratocan rtTA/Tet-O-sFRP1 (KR/sFRP1). Bitransgenic mice were generated by breeding keratocan/rtTA knock-in (KR/rtTA) mice with tetracycline-On promoter-driven sFRP1 (Tet-O-sFRP1). Bitransgenic mice expressed sFRP1 in corneal stroma upon doxycycline induction. (b) Corneal stromal expression of reporter gene GFP in adult KR/GFP mice. (c, d) Immunostaining verified that only bitransgenic KR/sFRP1 mice were positive for sFRP1 in the corneal stroma. Abbreviations: cn = cornea, cj = conjunctiva, ep = epithelium, and st = stroma.