Abstract: There is disclosed a novel genus of small peptides, much smaller than human TGF?, was discovered as having TGF? biological activity and therefore are useful as pharmacologic agents for the same indications as full length TGF? polypeptide. There is further disclosed that TGF? and consequently the genus of small peptides disclosed herein, was found to have therapeutic activity to stimulate hematopoiesis in patients undergoing cytotoxic cancer chemotherapy and to act as a cytoprotective agent to protect a patient undergoing cancer cytotoxic therapy from gastrointestinal (GI) side effects, such as mucositis and otherwise support the barrier function of the GI tract when it is harmed by cytotoxic therapy.