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Suppression of Fas-signaling by FLIP. The TNF-family receptor Fas contains a cytosolic DD that binds the bipartite adapter protein, FADD. The DD of FADD interacts with Fas, and its DED binds the DEDs in pro—Caspase-8. Recruitment of pro—Caspase-8 to clustered receptors on the plasma membrane induces proteolytic processing and activation of pro—Caspase-8, releasing the active protease into the cytosol. FLIP contains DED domains that compete for binding to pro—Caspase-8 and FADD, squelching signaling by Fas. Over-expression of FLIP occurs in many cancers.

One of the blasts from this patient with FAB M1 AML contains a prominent Aver rod. (Four-color version of figure on CD-ROM)

The characteristic histologic appearance of a resected osteoid osteoma. The tumor or nidus located in the lower right hand portion of the specimen contains richly anastomosing vascular channels as well as nerve fibers. There is calcification within this lesion. The lesion is surrounded by dense sclerotic reactive bone (Courtesy of Dr. Joseph Mirra).

Biochemical steps for nucleotide excision repair of CPDs. Initial recognition of damage involves the XPC and E gene products, followed by XPA and RPA that bind to photoproducts and download the helicases XPB and D for local unwinding. Excision occurs when UV-specific endonucleases (XPF/ERCC1 and XPG) make incisions on the 5′ and 3′ sides. Excision and subsequent polymerization releases a 29-base oligonucleotide that contains the CPD.