The observed decrease in the intensity of p-ERK1/2 immunohistochemical staining in the SHR cortex and in medulla of DOCA-salt animals may also be caused by a decrease in kinase activity or an increase in phosphatase levels (perhaps CacyBP/SIP performs this function) and be important in the pathology of primary and secondary hypertension. This evidence concerns the gene MAPK3 and secondary hypertension.