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Molecular biology is cool. There are a bunch of proteins in signaling transduction pathways we still don't know the function of. There are still a bunch of proteins we still don't know the 3D structure of. If you can find the structure, you can potentially find drug candidates to inhibit it/activate it. Also, you can get a ton of grant money for this stuff once you've proven your merit. Only problems are that it's a lot of work, and it takes a long time to get your phd to qualify for grants, the grant writing process is a pain, much harder then writing the actual final paper btw, somebody will probably publish your result right before you do, most people won't really care about your individual ideas, including the senior professors, until you do enough that they can cash in easily on your work, and then they will receive most the credit. If all that sounds like a hoot to you, then have at it! You also could work for a drug company, that will lay workers off just randomly just to scare you into working harder without an increase in pay. Again, any discovery goes to the company not you.
