We recently observed that sulfopolysaccharides isolated from sea algae can inhibit the ATP-hydrolyzing ectonucleotidases NPP1 (CD203a; CD, cluster of differentiation) and NTPDase1 (CD39) (11), enzymes whose important role in cancer proliferation, angiogenesis, metastasis, and immune escape is increasingly recognized (12, 13). This evidence concerns the gene ENPP1 and cancer.