Regeneration and the mechanism of XXXX .

@entity864 @entity5 @entity19 @entity1373 @entity5072 @entity865 @entity105
Chemically induced @entity105 is often divided into two stages: initiation, which involves the conversion of some epidermal cells into latent neoplastic cells, and promotion, which allows the evolution of this neoplastic change into the formation of a @entity5 . The hallmark of @entity5 is the transformation of the normal epidermis into a @entity5072 . A major unanswered question about @entity5 is whether the @entity1373 that characterizes promoted skin is a @entity1373 resulting from damage produced by the promoter. The opinion currently held is that the @entity1373 produced by @entity5 promoters is not simply a @entity1373 and possesses characteristics which a regenerative @entity1373 does not have, enabling it to evolve into an epidermal @entity5 . The purpose of this review is to present recent evidence which strongly suggests that promoter-induced @entity1373 is a regenerative @entity1373 . Three principal lines of evidence are reviewed. The first demonstrates that an epidermal regenerative @entity1373 repeatedly produced by wounding or abrasion can promote @entity105 in the initiated skin of @entity19 . The second line of evidence demonstrates that the @entity1373 produced by the application of @entity864 ( @entity865 ), the most powerful and widely used promoter of @entity105 , is preceded by damage to the epidermis. This strongly suggests that the @entity1373 which ensues is a regenerative @entity1373 . Thirdly, evidence is presented which demonstrates that @entity1373 -producing agents which do not promote, produce an @entity1373 which is different from that produced by @entity5 promoters. Finally, the review discusses the evidence which suggests that the production of a @entity1373 may be the mechanism for @entity5 promotion in other organs, such as the liver, bladder, and intestine.
