Because our medicine is categorized by specialty: lung specialist, endocrinologist, neurologist, so on.
Adenocarcinoma is equal colon cancer, pancreatic cancer, lung cancer,stroke, and other cancers that cannot be detected by MRI. Because it is hormonal in origin and its course is 2 months (death happens quickly) but it started 20 yrs ago from indigestion and exposure to toxins (turns off/on our genes).
Gene activations and metabolism alterations are examples of cellular responses to extracellular stimulation that require signal transduction. Gene activation leads to further cellular effects, since the products of responding genes include instigators of activation; transcription factors produced as a result of a signal transduction cascade can activate even more genes. Hence, an initial stimulus can trigger the expression of a large number of genes, leading to physiological events like the increased uptake of glucose from the blood stream and the migration of neutrophils to sites of infection. The set of genes and their activation order to certain stimuli is referred to as a genetic program.
Mammalian cells require stimulation for cell division and survival; in the absence of growth factor, apoptosis ensues. Such requirements for extracellular stimulation are necessary for controlling cell behavior in unicellular and multicellular organisms; signal transduction pathways are perceived to be so central to biological processes that a large number of diseases are attributed to their disregulation. Three basic signals determine cellular growth:
- Stimulatory (growth factors)Transcription dependent response
For example, steroids act directly as transcription factor (gives slow response, as transcription factor must bind DNA, which needs to be transcribed. Produced mRNA needs to be translated, and the produced protein/peptide can undergo Posttranslational_modification (PMT))Transcription independent response
For example, epidermal growth factor (EGF) binds the epidermal growth factor receptor (EGFR), which causes dimerization and autophosphorylation of the EGFR, which in turn activates the intracellular signaling pathway .
- Inhibitory (cell-cell contact)
- Permissive (cell-matrix interactions)
The combination of these signals are integrated in an altered cytoplasmic machinery which leads to altered cell behaviour.
More about cancer at Senior care and Disease Prediction