We have isolated an @entity6824 -like membrane-associated growth factor from @entity1 leukemic J6-1 cells that can enhance the growth and colony formation of J6-1 cells in vitro. Indirect evidence suggests that this membrane-associated @entity6824 -like growth factor may do so by stimulating a corresponding receptor co-expressed on the adjacent J6-1 cells. The objective of this study is to isolate the putative receptor in J6-1 cells by virtue of its ability to bind and thus "block" the growth of J6-1 cells. Based on this approach, we have isolated from the J6-1 cell membrane an inhibitory activity that can inhibit the clonal growth of J6-1 cells. The activity of this inhibitor can be readily neutralized by either anti-M- @entity6823 MAb or anti-M- @entity6823 antiserum, suggesting that it is related to M- @entity6823 , a product of @entity6823 proto-oncogene. Judging from Sephadex G-200 gel filtration, the molecular weight (MW) of this putative M- @entity6823 -like inhibitor was estimated to be approx. 150-180 kDa, comparable with that of M- @entity6823 . The specificity of M- @entity6823 -like protein to recognize and block membrane-bound @entity6824 also was implicated by its ability to upregulate the steady-state levels of @entity6823 mRNA in J6-1 cells. Besides its antiproliferative activity in vitro, treatment of J6-1 cells with the putative receptor protein before inoculation effectively blocked the growth and @entity5 formation in vivo by J6-1 cells in a nude @entity19 model. These findings suggest that the growth and @entity5 development by J6-1 leukemic cells may involve a contact-mediated "juxtacrine mechanism".

Enhancement of J6-1 @entity1 leukemic cell proliferation by membrane-bound @entity6824 through a cell-cell contact mechanism II. Role of an XXXX receptor-like membrane protein.

@entity1 :: ('9606', 'Species') :: ['human'] @entity19 :: ('10090', 'Species') :: ['mouse'] @entity6823 :: ('1436', 'Gene') :: ['CSFR', 'c-fms'] @entity5 :: ('MESH:D009369', 'Disease') :: ['tumor'] @entity6824 :: ('1435', 'Gene') :: ['M-CSF']
@entity6824 :: (1435,Gene) :: ['M-CSF']
