title: Calcium, magnesium, and serum factors in multiplication of normal and transformed human lung fibroblasts.
abstract: Serum factors determine the extracellular requirement for both Ca2+ and Mg2+ for multiplication of normal human lung fibroblasts in vitro. Serum factors also affect the extracellular Ca2+ requirement for transformed fibroblasts but to a different extent than for normal cells. Transformed cells exhibit a reduced requirement for both Ca2+ and Mg2+ for multiplication. The apparent reduction in Ca2+ requirement of transformed cells is dependent on the level of serum factors in the medium. The reduced Mg2+ requirement for transformed cells is more striking than the loss of Ca2+ and independent of the level of serum factors in the medium. A sequential effector relationship among serum factors, Ca2+ and Mg2+, in a proliferative control system for normal cells is proposed. Alteration or bypass of an intracellular Mg2+-requiring process is proposed as a major lesion in the transformed cells. This alteration causes an observed loss of requirements for both Ca2+ and serum factors for the multiplication of transformed cells.
mesh_terms: D001769:Blood; D002118:Calcium / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002472:Cell Transformation, Viral; D005347:Fibroblasts; D006801:Humans; D007700:Kinetics; D008168:Lung; D008274:Magnesium / Q000494:pharmacology*; D008954:Models, Biological; D013539:Simian virus 40 / Q000502:physiology
chemical_list: D008274:Magnesium; D002118:Calcium