These activities focused largely on the cell's intracellular biochemical network and relied less on molecular cues from its immediate surroundings.
In response to molecular cues from death stimuli, mitochondria release molecules known as apoptosis inducing factors, cytochrome c (cyto c) and generate reactive oxygen species (ROS) in resulting cell death [1], [2].
Additionally, molecular cues from stromal cells provide the signaling to maintain and expand the stem cell phenotype.
Molecular cues from stromal cells or the extracellular matrix will provide the signaling to maintain and expand the stem cell phenotype.
During development, specific molecular cues from the tumor microenvironment can play a role in maintaining and expanding stemness of cancer cells.
Since the work of Gussoni that firstly described the presence of haematopoietic stem cells (HSCs) in adult skeletal muscle [ 60], it was demonstrated that these cells could be recruited according to specific molecular cues from bone marrow to muscle, where they actively participated in muscle regeneration [ 61].
While in most mitotic cells, the cues that direct cell polarization are often extrinsic, coming from the environment or certain cortical landmarks [13], [14], the molecular cues for asymmetric meiotic divisions of oocytes remain poorly understood.
The molecular cues for this recognition remain unknown.
Recently attributed to stochastic events which increase the likelihood of a specific developmental outcome [22], this view is in direct opposition to determinism, which precludes the processing of molecular cues emanating from the cellular niche.
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].
