Full-length Slit and Slit-N are loosely associated with the ECM, whereas Slit-C is tightly bound to the ECM.

Extracts were derived from ~16 hours old embryos and were prepared under identical conditions unless otherwise noted. Tubulin was used as a loading control. (A): Full-length Slit is detected in the media only with >4 mechanical strokes of embryonic cells in a Dounce homogenizer. Slit-C is not detected in these samples either in the cells-pellet extracts or in the media. (B, C): The Slit-N peptide is readily detected in total embryo extracts with anti-Slit-N (B), whereas the Slit-C fragment is rarely detected in total embryo extracts with anti-Slit-C (C). Both antibodies readily detect full-length Slit. (D): Slit-C is readily detected in the supernatant of embryonic cells treated with collagenase but is not detected without the collagenase treatment. (E): Slit-C is also present in axon tracts as indicated by its presence in the collagenase-treated supernatant in ptc mutant embryos.