[1] Stanford Univ, Howard Hughes Med Inst, Sch Med, Stanford, CA 94305 USA
[2] Stanford Univ, Program Epithelial Biol, Sch Med, Stanford, CA 94305 USA
[3] Stanford Univ, Dept Bioengn, Stanford, CA 94305 USA
[4] Weizmann Inst Sci, IL-76100 Rehovot, Israel
[5] Dept Comp Sci & Appl Math, IL-76100 Rehovot, Israel