STK4（serine/threonine kinase 4），癌症关联基因，基因ID：6789，该基因编码的蛋白质是一种细胞质激酶，其结构类似于酵母ste20p激酶，作用于应激诱导的有丝分裂原激活蛋白激酶级联的上游。编码的蛋白能磷酸化髓鞘碱性蛋白并进行自磷酸化。编码蛋白的caspase裂解片段能够磷酸化组蛋白H2B，该蛋白催化的特异磷酸化与细胞凋亡有关，可能是该蛋白诱导染色质缩合[由RefSeq提供，2008年7月]The protein encoded by this gene is a cytoplasmic kinase that is structurally similar to the yeast Ste20p kinase， which acts upstream of the stress-induced mitogen-activated protein kinase cascade. The encoded protein can phosphorylate myelin basic protein and undergoes autophosphorylation. A caspase-cleaved fragment of the encoded protein has been shown to be capable of phosphorylating histone H2B. The particular phosphorylation catalyzed by this protein has been correlated with apoptosis， and it's possible that this protein induces the chromatin condensation observed in this process. [provided by RefSeq， Jul 2008]。