In fact, our data not only show that silencing DYRK1A gene expression potentiates and significantly increases the response of colon and breast cancer cells to G1/S targeting chemotherapy treatments but also highlight the DYRK1A kinase small molecule inhibitor, harmine as a potent chemotherapy sensitizer when used in combination therapy with topotecan and cisplatin. The gene discussed is DYRK1A; the disease is breast carcinoma.