Signaling components such as mitogen-activated protein kinases (MAPKs) regulate stress-induced pathways and are potentially a powerful means of genetically engineering plant tolerance to abiotic stress. The kinase domain of tobacco mitogen-activated protein kinase Nicotiana protein kinase 1 (NPK1) into rice cultivar Nipponbare. Four-week old transgenic and wild type plants treated with moderate (150mM) or severe (300mM) salt stress did not differ in visible signs of leaf damage, electrolyte leakage, malondialdehyde content or ion content within leaves. Expression of caNPK1 alters gene transcript abundance in the absence of stress as assessed by microarray analysis. Genes potentially related to flowering and development are downregulated while biotin biosynthesis and methionine recycling pathway as well as thirteen transcripts with matches to stress-related genes appear upregulated in the transgenic plants. Quantitative real-time PCR analysis indicates no significant difference in expression of several known rice MAPKs between caNPK1 transgenics and wild type.