The control of human WI-38 cell proliferation by extracellular calcium and its elimination by SV-40 virus-induced proliferative transformation.

The proliferative activity of diploid human WI-38 cells in sparse cultures depends on the extracellular concentration of free (or physiologically available) calcium, and cultivation in a medium having a calcium concentration of 0.1 mM or less gradually, but reversibly, arrest their proliferative development in the prereplicative (G1) phase of the cell cycle. Calcium's proliferative control of this cell type is eliminated by proliferative and morphological transformation by the oncogenic SV-40 virus, and the proliferative activity of SV-WI-38 cells in sparse cultures is unaffected by variation of the extracellular free calcium concentration between 0.00 and 1.25 mM.