Considering the bioactivities exhibited by microalgae, the effect of protein extract of Chlorella minutissimma (CPextract) was investigated on the expression of human matrix metalloproteinases-1 (MMP-1) in the breast cancer cell lineMDA-MB231, and that of MMP-2 and -9 in hepatocellular cancer cell line HepG2 at different expression levels. This evidence concerns the gene MMP2 and breast cancer.