TESK2 is a dual-specificity protein kinase that catalyzes phosphorylation of both serine/threonine and tyrosine residues 1. The kinase specifically phosphorylates cofilin at serine-3, inducing actin cytoskeletal reorganization, stress fiber formation, and focal adhesion assembly 2. Unlike its homolog TESK1, TESK2 localizes predominantly to the nucleus in a kinase activity-dependent manner and is primarily expressed in testicular Sertoli cells rather than germ cells 2. TESK2 plays a critical role in spermatogenesis, with expression predominantly in round spermatids after postnatal day 30 1. Beyond reproduction, TESK2 has emerged as relevant to several disease states. In preeclampsia, mendelian randomization and colocalization analyses confirmed TESK2 as a causal genetic target, with single-cell RNA sequencing supporting its association with disease development 3. TESK2 expression is silenced through epigenetic mechanisms in epi-cblC, an inherited disorder of vitamin B12 metabolism affecting hematological, neurological, and cardiometabolic outcomes 4. In cancer contexts, low TESK2 expression associates with poor survival in head and neck squamous cell carcinoma 5 and lung adenocarcinoma 6, and apomorphine treatment targeting TESK2 prevented brain metastasis formation in preclinical models 6.