Peptides are provided that comprise less than 24 amino acids. The peptides have an amino acid sequence selected from the group consisting of: (a) an amino acid sequence having from 4 to 6 contiguous amino acids of a reference sequence PEPTIDE 1; (b) an amino acid sequence substantially identical to the sequence defined in (a); and (c) a variant of the amino acid sequence defined in (a). Also provided is a non-myristoylated MANS peptide. Various methods of using the peptides are also provided.