The invention provides novel polynucleotides and polypeptides encoded by such polynucleotides and mutants or variants thereof that correspond to a novel human secreted stem cell growth factor-like polypeptides. In particular, the invention relates to novel stem cell growth factor-like polypeptides, including novel proteins named SCGF3248Fk081_aa2, SCGF3248Fk081_aa1, SCGFFk081_aa3, and SCGF323401Fe131_aa1. Other aspects of the invention include vectors containing processes for producing novel human secreted stem cell growth factor-like polypeptides, and antibodies specific for such polypeptides.