The similarity of the context-dependent suppression of proliferation of chr4p genes to chr13q, a region deleted in ∼45% of basal breast cancers, which also harbors a PDCD10 heterodimerization partner, STK24, highlights the important role of PDCD10-kinase module stoichiometric balance in exerting selection pressures on copy-number evolution of the breast cancer genome. The gene discussed is PDCD10; the disease is breast cancer.