CDK2 and breast cancer: Based on the results of the PA analysis using PamChip peptide microarray-based kinase activity profiling, it can be concluded that the Hsp90-mediated VEGFR-2 pathway is an important target, beside the importance of the cell cycle G1/S phase and its related growth regulators CDK2/cyclin D1 in addition to the importance of the phosphorylation processes in the tumorigenesis of Saudi luminal-A breast cancer samples.