An isolated nucleic acid molecule selected from the group consisting of: (a) a nucleic acid molecule comprising the nucleotide sequence set forth in SEQ ID NO: 1 or 4, or a complement thereof which is complementary to said nucleic acid sequence over its full length; (b) a nucleic acid molecule comprising the nucleotide sequence set forth in SEQ ID NO: 3 or 6, or a complement thereof which is complementary to said nucleic acid sequence over its full length; (c) a nucleic acid molecule which encodes a polypeptide comprising the amino acid sequence set forth in SEQ ID NO: 2 or 5, or a complement thereof which is complementary to said nucleic acid sequence over its full length; (d) a nucleic acid molecule which encodes a naturally occurring allelic variant of a polypeptide comprising the amino acid sequence set forth in SEQ ID NO: 2 or 5, or a complement thereof which is complementary to said nucleic acid sequence over its full length; (e) a nucleic acid molecule comprising a nucleotide sequence which is at least 75% identical to the nucleotide sequence of SEQ ID NO: 1 or 3, or a full-length complement thereof which is complementary to said nucleic acid sequence over its full length; (f) a nucleic acid molecule comprising a nucleotide sequence which is at least 95% identical to the full-length nucleotide sequence of SEQ ID NO: 4 or 6, or a complement thereof which is complementary to said nucleic acid sequence over its full length; (g) a nucleic acid molecule which encodes a polypeptide comprising an amino acid sequence at least about 75% identical to the full-length amino acid sequence of SEQ ID NO: 2, or a complement thereof which is complementary to said nucleic acid sequence over its full length; and (h) a nucleic acid molecule which encodes a polypeptide comprising an amino acid sequence at least about 95% identical to the full-length amino acid sequence of SEQ ID NO: 5, or a complement thereof which is complementary to said nucleic acid sequence over its full length. (a) a nucleic acid molecule comprising the nucleotide sequence set forth in SEQ ID NO: 1 or 4, or a complement thereof which is complementary to said nucleic acid sequence over its full length; (b) a nucleic acid molecule comprising the nucleotide sequence set forth in SEQ ID NO: 3 or 6, or a complement thereof which is complementary to said nucleic acid sequence over its full length; (c) a nucleic acid molecule which encodes a polypeptide comprising the amino acid sequence set forth in SEQ ID NO: 2 or 5, or a complement thereof which is complementary to said nucleic acid sequence over its full length; (d) a nucleic acid molecule which encodes a naturally occurring allelic variant of a polypeptide comprising the amino acid sequence set forth in SEQ ID NO: 2 or 5, or a complement thereof which is complementary to said nucleic acid sequence over its full length; (e) a nucleic acid molecule comprising a nucleotide sequence which is at least 75% identical to the nucleotide sequence of SEQ ID NO: 1 or 3, or a full-length complement thereof which is complementary to said nucleic acid sequence over its full length; (f) a nucleic acid molecule comprising a nucleotide sequence which is at least 95% identical to the full-length nucleotide sequence of SEQ ID NO: 4 or 6, or a complement thereof which is complementary to said nucleic acid sequence over its full length; (g) a nucleic acid molecule which encodes a polypeptide comprising an amino acid sequence at least about 75% identical to the full-length amino acid sequence of SEQ ID NO: 2, or a complement thereof which is complementary to said nucleic acid sequence over its full length; and (h) a nucleic acid molecule which encodes a polypeptide comprising an amino acid sequence at least about 95% identical to the full-length amino acid sequence of SEQ ID NO: 5, or a complement thereof which is complementary to said nucleic acid sequence over its full length.