D. CCNA, CCNB2 and Cdk1 expression transcripts were analyzed by RT-qPCR in cDNA derived from MDA-MB-231 (left panel) and SKBr3 (right panel) cell lines treated or not with 1 µM Cer for 48h. Error bars represent mean + s.d., from three biological replicates. P-values were calculated with two-tailed t-test. P-value<0.01. 