As a major microtubule-organizing center, the centrosome, together with the embedded centrioles and connecting filaments (or microtubules), has lately been proposed to be the "brain" of a cell. Although there are a lot of works to be done to test this hypothesis, emerging data have suggested that this centrosome-centered "cell brain" is playing increasingly important roles in cell control. Genes seem not to tell the whole story, despite the commonly held view that genetic alteration is the cause of most medical problems including cancer development. Although the mechanisms through which gene expression and protein synthesis are regulated remain to be studied, current advances in our understanding of the roles of the centrosome in the regulation of DNA synthesis, DNA repair, cell cycle, apoptosis and in the maintenance of genetic stability are challenging our tradition thoughts. Genetic alterations may be repaired by the centrosome-centered "cell brain"-mediated self-defense, but the cell brain defects intend to cause genetic alterations, which, in turn, may result in cancer development. Further understanding of the roles of the centrosome/cell brain in these and other new aspects are becoming very helpful in comprehending why and how medical problems including tumors develop. Meanwhile, it suggests that great attention should be given to the centrosome/cell brain, instead of gene alone when treating medical problems, which is discussed in this paper on the basis of cell brain theory and may prove helpful in shedding light on the often paradoxical observations seen in cell control, particularly in cancer development.