Under pathological conditions (e.g. MPNs), the Zhan group used mice expressing the JAK2V617F mutation specifically in ECs (found in some MPN patients; using Tie2-Cre), to study the effect of the JAK2V617F-bearing vascular niche on MPN disease development in vivo (80). The authors observed thrombocytosis and clusters of Mks preferentially located near sinusoids, associated with reticulin fibrosis. Here, TEK is linked to myeloproliferative neoplasm.