Somatomedin B: mitogenic activity derived from contaminant epidermal growth factor.

The mitogenic effect of somatomedin B on human cultured glial cells was neutralized by the addition of antibodies to mouse epidermal growth factor. Somatomedin B contained epidermal growth factor--like activity, competing for binding to the epidermal growth factor receptor. It is concluded that contaminating epidermal growth factor may explain the entire mitogenic activity of somatomedin B.