The present invention provides methods and compositions for the inhibition of proliferation rate of target cells, for example tumor cells. In particular, a nucleic acid encoding a connexin protein, fragment, derivative or analog thereof can be incorporated into a target cell. Expression of the nucleic acid sequence encoding the connexin protein, fragment, derivative or analog thereof, particularly connexin 43 and non-phosphorylated connexin 43, reduces the level of bc1-2 expression in the cells thereby inducing the cells to enter apoptosis. Connexin protein, fragments, derivatives, or analogs thereof can also be administered to the cell population to reduce bc1-2 expression inducing apoptosis in the cell population. It has further been found that the addition of an antagonist of MCP-1 activity can enhance the effects of connexin on tumor cell proliferation. Also, the prognosis of a subject undergoing standard chemotherapy can be assessed by correlating the expression levels of connexin and bc1-2.
