@entity1778 virus (FLV) that are associated with @entity6582 contain the defective @entity18903 ( @entity18903 ). To determine whether the transforming ability of FLV was affected by the presence of this second agent, @entity7840 /2J @entity19 bone marrow cells were infected in vitro. Criteria for transformation were the establishment of permanent lines, growth on semisolid agarose, and the production of @entity5 at the site of inoculation in syngeneic hosts. Two lines of immature hematopoietic cells that grow in suspension originated from the infected cultures. Each has an almost diploid karyotype (38-39 chromosomes) and 3-4 metacentric chromosomes. These transformed cells express gp71 viral envelope glycoprotein and @entity9510 viral core protein antigens. Virus production was measured by reverse transcriptase (RNA-dependent DNA polymerase) activity of the virions released into the medium. The virus, assayed in vivo for infectivity, has @entity18903 activity but is attenuated for leukemogenicity. The stimulation of hemoglobin synthesis in the cells grown in medium supplemented with @entity3733 or @entity16747 indicates that the cells are erythroid in origin. @entity18903 may have a function analogous to erythropoietin in influencing the process of transformation by FLV.

In vitro transformation of XXXX bone marrow cells by the polycythemic strain of @entity1778 virus.

@entity6582 :: ('MESH:D011086', 'Disease') :: ['polycythemia'] @entity19 :: ('10090', 'Species') :: ['mouse'] @entity5 :: ('MESH:D009369', 'Disease') :: ['tumors'] @entity3733 :: ('MESH:D004121', 'Chemical') :: ['dimethyl sulfoxide'] @entity1778 :: ('MESH:D007938', 'Disease') :: ['Strains of Friend leukemia'] @entity16747 :: ('MESH:C014026', 'Chemical') :: ['hexamethylene bisacetamide'] @entity18903 :: ('11819', 'Species') :: ['spleen focus-forming virus', 'SFFV'] @entity7840 :: ('CHEBI:35299', 'Chemical') :: ['DBA'] @entity9510 :: ('201161', 'Gene') :: ['p30']
@entity19 :: (10090,Species) :: ['mouse']
