Saethre-Chotzen syndrome (SCS), associated with TWIST-1 mutations, is 
characterized by premature fusion of cranial sutures. TWIST-1 
haploinsufficiency, leads to alterations in suture mesenchyme cellular gene 
expression patterns, resulting in aberrant osteogenesis and craniosynostosis. We 
analyzed the expression of the TWIST-1 target, Tyrosine kinase receptor 
c-ros-oncogene 1 (C-ROS-1) in TWIST-1 haploinsufficient calvarial cells derived 
from SCS patients and calvaria of Twist-1del/+ mutant mice and found it to be 
highly expressed when compared to TWIST-1 wild-type controls. Knock-down of 
C-ROS-1 expression in TWIST-1 haploinsufficient calvarial cells derived from SCS 
patients was associated with decreased capacity for osteogenic differentiation 
in vitro. Furthermore, treatment of human SCS calvarial cells with the tyrosine 
kinase chemical inhibitor, Crizotinib, resulted in reduced C-ROS-1 activity and 
the osteogenic potential of human SCS calvarial cells with minor effects on cell 
viability or proliferation. Cultured human SCS calvarial cells treated with 
Crizotinib exhibited a dose-dependent decrease in alkaline phosphatase activity 
and mineral deposition, with an associated decrease in expression levels of 
Runt-related transcription factor 2 and OSTEOPONTIN, with reduced PI3K/Akt 
signalling in vitro. Furthermore, Crizotinib treatment resulted in reduced BMP-2 
mediated bone formation potential of whole Twist-1del/+ mutant mouse calvaria 
organotypic cultures. Collectively, these results suggest that C-ROS-1 promotes 
osteogenic differentiation of TWIST-1 haploinsufficient calvarial osteogenic 
progenitor cells. Furthermore, the aberrant osteogenic potential of these cells 
is inhibited by the reduction of C-ROS-1. Therefore, targeting C-ROS-1 with a 
pharmacological agent, such as Crizotinib, may serve as a novel therapeutic 
strategy to alleviate craniosynostosis associated with aberrant TWIST-1 
function.