In this task, you are given an abstract of article. Your task is to generate title for this article. Preferred titles are under thirty words.

Example Input: Publisher Summary This chapter discusses the developmental roles of vascular endothelial growth factor (VEGF) in skeletal morphogenesis, speculates on the future directions of research in this area, and describes some of the challenges in the field. VEGF regulates osteoclastic differentiation, migration, and activity. VEGF is, therefore, a key coordinator of the entire process. VEGF is necessary for osteoclastic activity both at the stage when the primary ossification center is established and later during bone growth. A number of studies have led to the identification of VEGF as a critical factor for the survival of chondrocytes. Several factors with important roles in regulating bone formation also induce the expression of VEGF by osteoblasts. Prostaglandins E1 and E2, BMP-4, BMP-6, BMP-7, FGF-2, TGF-, endothelin-1, IGF-1, and vitamin D3 can all induce VEGF expression in osteoblasts by activating a variety of signaling pathways. Bone fractures can heal in two divergent ways, similar to the two ways of forming bone during embryonic development. Stabilized fractures heal by intramembranous ossification, and unstable fractures undergo endochondral ossification. The similarity between the embryonic bone development and repair of fractured bones, coupled with the finding that VEGF is expressed at sites of bone fracture, suggests that VEGF is involved in bone repair as it is in bone development.
Example Output: Multiple roles of vascular endothelial growth factor (VEGF) in skeletal development, growth, and repair.

Example Input: Imaging techniques have greatly improved our understanding of lymphocyte activation. Technical advances in spatial and temporal resolution and new labelling tools have enabled researchers to directly observe the activation process. Consequently, research using imaging approaches to study lymphocyte activation has expanded, providing an unprecedented level of cellular and molecular detail in the field. As a result, certain models of lymphocyte activation have been verified, others have been revised and yet others have been replaced with new concepts. In this article, we review the current imaging techniques that are used to assess lymphocyte activation in different contexts, from whole animals to single molecules, and discuss the advantages and potential limitations of these methods.
Example Output: Imaging techniques for assaying lymphocyte activation in action

Example Input: Astrocyte differentiation, which occurs late in brain development, is largely dependent on the activation of a transcription factor, STAT3. We show that astrocytes, as judged by glial fibrillary acidic protein (GFAP) expression, never emerge from neuroepithelial cells on embryonic day (E) 11.5 even when STAT3 is activated, in contrast to E14.5 neuroepithelial cells. A CpG dinucleotide within a STAT3 binding element in the GFAP promoter is highly methylated in E11.5 neuroepithelial cells, but is demethylated in cells responsive to the STAT3 activation signal to express GFAP. This CpG methylation leads to inaccessibility of STAT3 to the binding element. We suggest that methylation of a cell type-specific gene promoter is a pivotal event in regulating lineage specification in the developing brain.
Example Output:
DNA methylation is a critical cell-intrinsic determinant of astrocyte differentiation in the fetal brain.