The ectopic cell deaths caused by overexpression of egl-1 can also be suppressed by ced-9(gf), ced-3(lf), or ced-4(lf) mutations. In contrast, the egl-1(lf) mutation can not suppress ectopic cell deaths caused by ced-9(lf) mutations (23). These results further support the
conclusion that egl-1 acts upstream of the ced-3, ced-4 and ced-9 genes. Genetic epistasis analysis on egl-1 and cell-death-specification genes ces-1 and ces-2 suggests that egl-1 is likely to act downstream of these death pecification genes. Since egl-1 is the earliest acting gene of the general
cell-death pathway identified so far and acts downstream of the death specification genes, egl-1 may play a crucial role in receiving cell death signals from the cell-death-specification genes and then initiating the activation of the cell death program.