The growth requirements of SV40 virus transformed Balb/C-3T3 cells in serum-free monolayer culture

The growth requirements of SV40 transformed Balb/c‐3T3 cells have been studied in the absence of serum. For growth in serum‐free medium, the cells require (i) insulin, (ii) transferrin, and (iii) cis‐unsaturated fatty acids added in combination with fatty acid free bovine serum albumin. The growth rate, saturation density, and morphology of cells grown in this serum‐free medium are the same as those of cells grown in serum supplemented medium. This mixture also supports the growth of SV40 transformed Swiss‐3T3 cells and SV40 transformed primary mouse embryo cells, but does not support the growth of untransformed Balb/c‐3T3 cells. The addition of fibronectin to this mixture allows routine subculture, repeated passage, and indefinite propagation of SV40 transformed Balb/c‐3T3 cells. Cells grown in this medium for a period of two months retain their ability to induce tumors when injected into athymic nude mice.