Fig. 11. S-1-P treatment of wild-type cells during development produces a phenocopy of the S-1-P lyase null mutant. Wild-type Ax4 cells were allowed to develop synchronously on filters (A,B). S-1-P was added at 5 (C,D), 8 (E,F) and 12 (G,H) hours of development, as described in Materials and Methods. The photographs were taken at 24 (A,C,E,G) and 60 (B,D,F,H) hours of development. 1 cm=2 mm.