A sterile, concentrated (20X) solution intended for use with Medium 231 to culture human smooth muscle cells. Each 25 ml bottle of SMGS contains all of the growth factors, hormones, and tissue extracts necessary for the culture of human smooth muscle cells, and is the correct amount of supplement for a 500 ml bottle of basal Medium 231. When a 500 ml bottle of medium is supplemented with SMGS, the final concentrations of the components in the supplemented medium are: Fetal bovine serum (4.9% v/v) Human basic fibroblast growth factor (2 ng/ml) Human epidermal growth factor (0.5 ng/ml) Heparin (5 ng/ml) Recombinant human insulin-like growth factor-I (2μg/ml) BSA (0.2μg/ml)