Hydrocortisone is used for at least two purposes in Lonza’s cell culture media. Hydrocortisone (in combination with low serum concentrations) will inhibit the takeover of the culture by fibroblasts which may be present in small numbers from the original cell isolation. While the hydrocortisone will not complete kill or prevent the growth of the contaminating fibroblasts, it will slow the proliferation down so that the other cell line may proliferate and dominate. Hydrocortisone will also help maintain the cells and provide longevity in later passages. Removing hydrocortisone for one passage should not have a noticeable effect, however for successive passaging, effects on proliferation and the potential for fibroblast growth may become more significant. Please note that Lonza cannot guarantee cell performance if any of the recommended supplements are excluded.