tissue inhibitors of matrix metallo proteinases (TIMPs) at the primary tumor
site.TIMPs inhibit the proteolytic activity of the matrix metalloproteinases
(MMPs) by inhibiting tumor invasion of the basement membrane or by
restraining tumor angiogenesis. TIMPs also appear to modulate tumor growth
and apoptosis of tumor cells. Downregulation of the anti-angiogenic peptides,
angiostatin and endostain, would enhance tumor growth (answer e). Angio-
statin is a cleavage product of plasminogen; endostatin is a cleavage product of
type XVIII collagen (see “High-Yield Facts,” Page 8 for more information on
angiogenesis). Antibodies to fibronectin, integrins, and laminin interfere with
metastasis. Enhancement of integrin-integrin receptor interactions would facil-
itate metastasis (answers a and b).Overexpression of selectins (answer c)on
endothelial cells could enhance sticking of tumor cells to the endothelium and
eventual extravasation.
122.The answer is d.(Junqueira, pp 103–104.)Type II collagen is found in
the nasal septum. Type I collagen (answer a)is ubiquitous, type III collagen
forms a reticular network in highly cellular organs (answer c),type IV colla-
gen is found in the basement membrane (answer d)and type VII collagen
(answer e)is found in the basement membrane of skin and forms anchoring
fibrils (see table page 184).
Specialized Connective Tissues: Bone and Cartilage Answers 215