ERBB2 and breast cancer: Considering that the serum starvation should not be used for studies that are not focused on cell cycle arrest, we studied the effect of silybin-phosphatidylcholine from Silybin AdvancedTM in 1:2 ratio (one part silybin bound to two parts phosphatidylcholine) on HER2 gene expression on the SKBR3 breast cancer cell line which were cultured in complete medium (not serum deprivation).