Schematics of representative deletions. (a) The deletion ofdaf-18 PTEN removes a portion of exon 3, which encodes the distal portion of the tensin homology domain and the catalytic phosphatase domain known to be required for lipid phosphatase activity (Gil et al. 1999). (b) The sel-12 deletion removes exons 3–6, which encode predicted transmembrane domains necessary for proper protein topology (Westlund 1998). (c) Thecdc-25 deletion removes the entire ORF.