human tumor cell lines , a rhabdomyosarcoma ( rd ) , and a fibrosarcoma ( ht-1080 ) were distinguished from normal human fibroblasts by tumorigenicity in athymic nude mice and immunosuppressed rats and hamsters , secretion of different types of collagen and procollagen molecules , and reduced amounts of fibronectin .
C0009325
collagen
C0033235
procollagen