Please explain yourself better, Chao. From what I undestand, a hyperactive element in a certain pathway can maintain it active and overexpressed for a long time. For example in tumors (where anomalies are frequent), a tyrosin-kinase abnormally active or a receptor functioning even without connection with a ligand, can maintain active entire methabolic pathways for a long time.

I think I should be more specific (meaning that I should send you back into uncertainty, I fear...), as the focus of the question is not entirely clear to me. Many pathways are cross-regulated by different factors/other pathways, depending on the biochemichal status of the cell/tissue/organism. I suppose one should know the mechanisms involved in the specific pathway one wishes to influence, or be ready to discover the existence of unexpected factors/interrelations.

Thanks, Black. My question is general because I know little about his but have too many questions. I wish to get a general picture about how the signaling is propagating or the basic motifs of signaling pathway. Is there some feedback mechanism to maintain the activation of part of the parthway? or it's just like a wave? Maybe this is not a good questions.

Hello

My friend worked and he published one paper regarding this. Go through the paper once. Here is link

http://www.omicsonline.org/0974-7230/JCSB-06-057.php?aid=12290

Sorry to be late. Questions, I hope, are never wrong. At least, being a student myself, I like to think it. One of our teachers mentioned to us that often in school made mistakes and gave terrible answers. Is the privilege of the one who learns, which means practically that this principle may apply anytime in life. Do not be afraid to be wrong and do not believe you will become perfect. I'm sure the old cinese wisdom will agree (hope not to be mistaken assuming you are cinese).

There are often feedbacks and interactions, maybe always. For example, in apoptosis, after the signal has been launched, the proapoptotic proteins can interact with antiapoptotic signals (if they exist in the circumstance) and the process may stop. Some factors triggering metabolic patways activate in the same time mechanisms that inhibit their own effects.

Interleukin 1, a very potent inflamatory signal, is a actually a complex of molecules: one has effects, another is inhibitory; also has more receptors: one is active, the other is a decoy that captures molecules of IL 1 blocking them. It is believed that due to the potential devastating effects of this molecule, the body has maintained functional simultaneous mechanisms to balance and tightly control its actions.

I studied molecular biology on a text that I liked very much, the author is Karp. You can also find many informations in general pathology and immunology books, for the beginning, in order to gather the knowledge that will help you deal with more specific and up to date articles. Is a beautiful and rich field, I wish you will enjoy it.

It really depends on what pathways you are talking about and in what context or cell type. For example G protein coupled receptors often have very complex signalling pathways within cells and alteration to any of the pathway components may have a large impact on the downstream products.

There are also many different types of signalling pathways; activation pathways, inhibition pathways, feedback pathways so there are many possible answers to your question. Also, there is often a lot of cross-talk between pathways which complicates things further. If you do have a specific cell type or signalling pathway in mind it would probably be easier to get better answers.

I hope this helps you in some way!