A method for inhibiting and/or preventing binding of RANK-L to RANK, wherein the method comprises at least the step of contacting RANK-L with at least one polypeptide that specifically binds to RANK-L, or with a composition comprising at least one polypeptide that specifically binds to RANK-L, wherein the at least one polypeptide comprises or essentially consists of 4 framework regions (FR1 to FR4 respectively) and 3 complementary determining regions (CDR1 to CDR3 respectively), in which:
- CDR1 is SEQ ID NO:
- 190, CDR2 is SEQ ID NO:
- 314, and CDR3 is SEQ ID NO:
- 438;
- CDR1 is SEQ ID NO:
- 193, CDR2 is SEQ ID NO:
- 317, and CDR3 is SEQ ID NO:
- 441;
- CDR1 is SEQ ID NO:
- 196, CDR2 is SEQ ID NO:
- 320, and CDR3 is SEQ ID NO:
- 444;
- or
- CDR1 is SEQ ID NO:
- 205, CDR2 is SEQ ID NO:
- 329, and CDR3 is SEQ ID NO:
- 453.