Endostatin was a 20 kDa c‐terminal fragment of collagen XVIII,10 originally isolated by O’ Reilly from supernatant of a murine hemangio‐endothelioma.11 In preclinical studies, endostatin was demonstrated to play key role in anti‐angiogenesis by normalizing tumor microvessels and inhibiting the activities of vascular endothelial cells via multiple targets.4, 12 It showed a strong suppression on various murine tumors growth in vivo, such as ovarian cancer,13 renal cell cancer,14 JC breast carcinoma,15 Lewis lung carcinoma, T241 fibrosarcoma, and B16F10 melanoma.10 Here, COL18A1 is linked to fibrosarcoma.