There is growing evidence that RWs act in combination with the expression of molecular cues such as ephrins [22], [26].
A diverse set of molecular cues, such as Dlx1/2 transcription factor regulated signals, motogenic factors such as BDNF, NT-4, and HGF, chemoattractants such as GDNF and NRG-1, as well as members of semaphorin family (3A, F) of chemorepellent factors, modulate the navigation of interneurons from the ganglionic eminence into the cerebral wall [1].
Molecular cues such as secretion of fibroblast growth factors (FGF-10, FGF-7) by the ectomesenchyme and expression of FGF receptors (FGF-R1, FGF-R2) by the epithelium are important for the development salivary gland [ 5, 43– 43].
As loss of integrity of compartment borders in the joint between cartilage and SF is a key event in RA, we were interested in analyzing molecular cues, such as the repellent factors, that might be deregulated in RA patients and thereby contribute to destruction of joint borders.
In spite of the absence of Ebf1 gene, no change is detected on the structure of neocortex, dorsal thalamus or even expression profiles of molecular guidance cues such as Cdh6, Coup-tfI.
The molecular cues responsible for defining the regionalisation of such a discrete pool of progenitors remain uncharacterised.
These rhythms could be regulated by either endogenous circadian molecular machinery [2], [3] or external abiotic cues such as the presence or absence of light or food [4], [5].
Activation of intracellular signaling pathways such as PI3K, Ras/Raf, and Jak/Stat by molecular cues emanating from the stem cell niche mediate phosphorylation events which control the activity of cyclin/CDK complexes and culminate in the modulation of genes (such as pRb and Trp53) that are implicated in cell cycle checkpoint, cell cycle exit, and differentiation [43].
Macrophages have a unique ability to alter their phenotypes and, thus, their functions, depending on tissue microenvironmental cues, such as the presence of cytokines, growth factors, pathogen-associated molecular pattern molecules (PAMPs), and damage-associated molecular pattern molecules (DAMPs).
Although all biological clocks are characterized by three diagnostic properties, (i) an internal timer ticking with an ∼24 h period, (ii) entrainment of the endogenous timer by exogenous cues such as light, and (iii) temperature compensation, the molecular players constituting the clock are not conserved across all organisms.
Molecular oscillators are entrained by external cues like light, and by internal cues, such as the activity of other pacemakers [e.g., 6].
