Aberrant expression of @entity8498 but not XXXX is a common feature of @entity2590 .

@entity33700 @entity1 @entity2590 @entity3052 @entity1778 @entity8498
The RAS gene family encodes signal transducing proteins which are involved in the regulation of cell growth and differentiation. Constitutively 'activating' point mutations of RAS have been detected at high frequency in preleukaemia and acute @entity1778 , however, the distribution of expression of @entity8498 in normal or preleukaemic primary haematopoietic cells has not been studied. We have examined the expression of @entity8498 and its negative regulator/downstream effector, @entity33700 , in combination with lineage-specific cluster of differentiation markers in normal and preleukaemic myeloid bone marrow cells using flow cytometry. Normal bone marrow was characterized by low and uniform levels of @entity8498 expression throughout all lineages analysed. In contrast, 28% (9/32) of @entity1 with @entity2590 ( @entity2590 ) over-expressed @entity8498 . In three of these @entity1 a single over-expressing peak of @entity8498 expression was observed, with no evidence of a population exhibiting expression within the normal range. In 6/32 @entity2590 @entity1 over-expression of @entity8498 was observed only in a subpopulation of the myeloid cells. Follow-up samples were analysed in three of these six @entity1 ; over-expression was confirmed in each @entity1 and in two @entity1 a relative expansion of the over-expressing cell population was observed. Eight out of nine of the @entity1 with aberrant @entity8498 expression were diagnosed with low-risk @entity2590 . From 21 @entity2590 @entity1 screened for @entity33700 expression, no reduction or loss of expression was observed, however, one @entity3052 @entity1 demonstrated a heterogeneous pattern of expression. @entity33700 expression was lower (P < 0.05) in the @entity3052 group than in normals. The results of the study suggest that over-expression of the RAS gene product, @entity8498 , may represent an alternative or additional mechanism of activation of the RAS signalling pathway and that this may play a role in leukaemogenesis, however, there is no evidence from this study that loss of @entity33700 expression is a feature of @entity2590 .
