ABSTRCT In mammals protein tyrosine phosphorylation plays an important role in the activation of programmed cell death. However, tyrosine phosphorylation involved in cell death has not been examined in plants. These studies demonstrated that D-mannose induced cell death and DNA fragmentation in rice suspension cells. In the presence of mannose for 24 hours, tyrosine phosphorylation of two proteins, 20 kDa and 43 kDa markedly increased. After incubating 3 days, the level of phosphotyrosine accumulation declined in bands of 16 and 20 kDa. In addition, the occurrence of DNA fragmentation and two tyrosine-phosphorylated proteins, 26 kDa and 40 kDa, were detected in aged suspension-cultured cells. The expression of genes that encode mitogen-activated protein kinase (MAPK) kinase (MEK)/MAPK signalling pathway, OsMEK and OsMAPK2, are up regulated during D-mannose treatment. The results provide evidence that protein tyrosine phosphorylation as well as MEK/MAPK signalling pathway is associated with cell death in rice.