1. A pharmaceutical composition comprising (i) a peptide of 50 amino acids or less comprising one of the following sequences (I), (II) and (IV) to (VII): 
 Z 1 —X 20 X 21 X 22 SLPTSPX 23 X 24 —Z 2 (VI); 
 Z 1 —X 4 ELDX 5 VFQX 6 X 7 —Z 2 (II); 
 Z 1 —X 1 LQEKFX 2 SX 3 —Z 2 (I); 
 Z 1 —X 11 X 12 VLKPGNX 13 X 14 —Z 2 (IV); 
 Z 1 —X 15 X 16 YDKGPFX 17 X 18 X 19 —Z 2 (V); or 
 Z 1 —X 25 X 26 X 27 GNPGTFX 28 X 29 —Z 2 (VII); wherein Z 1 is an amino terminal modifying group or is absent; X 1 is a sequence of 1 to 43 amino acids or is absent; X 2 is L or S; X 3 is a sequence of 1 to 43 amino acids or is absent; X 4 is a sequence of 1 to 43 amino acids or is absent; X 5 is G or R; X 6 is an amino acid or is absent; X 7 is a sequence of 1 to 43 amino acids or is absent; X 11 is a sequence of 1 to 43 amino acids or is absent; X 12 is S or T; X 13 is an amino acid or is absent; X 14 is a sequence of 1 to 43 amino acids or is absent; X 15 is a sequence of 1 to 43 amino acids or is absent; X 16 is an amino acid or is absent; X 17 is R or W; X 18 is an amino acid or is absent; X 19 is a sequence of 1 to 43 amino acids or is absent; X 20 is a sequence of 1 to 43 amino acids or is absent; X 21 is an amino acid or is absent; X 22 is an amino acid or is absent; X 23 is G or R; X 24 is a sequence of 1 to 43 amino acids or is absent; X 25 is a sequence of 1 to 43 amino acids or is absent; X 26 is an amino acid or is absent; X 27 is an amino acid or is absent; X 28 is K or N; X 29 is a sequence of 1 to 43 amino acids or is absent; and Z 2 is a carboxy terminal modifying group or is absent and (ii) a pharmaceutically acceptable carrier.