Axl, Dtk and Mer are recently described receptors that constitute a ne
w receptor tyrosine kinase subfamily. They bind the vitamin K-dependen
t protein growth-arrest-specific gene 6 (Gas6) that is structurally re
lated to the anticoagulation factor protein S. Studies suggest a role
for these receptors in developmental processes, in the function of the
hematopoietic and nervous systems and in tumorigenesis.