We show here that (i) mouse endocan is also a proteoglycan containing a single chondroitin sulfate chain; (ii) the secreted mouse endocan is variably glycanated; (iii) mouse endocan inhibits spontaneous tumor growth; (iv) non glycanated mouse and human endocan act similarly in delaying growth of various experimental tumors; (v) stromal inflammatory reaction is observed in tumors overexpressing endocan polypeptide; (vi) the anti-tumor property of endocan polypeptide requires the presence of CD122+ cells. The gene discussed is ESM1; the disease is neoplasm.