Something I forgot to mention: if you are considering returning to India after your PhD (and perhaps even if not), you may also want to consider what kind of reputation your school has at home. It seems, from what I have seen, that UW-Madison has an excellent reputation in India, especially for natural sciences and engineering. I would presume UCSD also has a very good, if not excellent reputation there, but I cannot say for sure.
What I can also say with some assurance (I have been on both campuses, and I am a UW alum) is that, while UCSD has many international students, UW has the arguably stronger resources in their international academic programs, particularly for languages, history, etc. What this means for somebody in your position is that, while you focus on molecular and cell biology, the strengths of the international programs do at times have a spill-over effect, in that the university presence and reputation benefit from strong international academic programs. In turn, this could have a mildly positive effect on your future career (but certainly not the most significant; the factors in the above posts would be more crucial).
Also, do know that as a state, California has had some difficult budget issues over the past few decades, with more severe effects on the University of California campuses than Wisconsin (which also has mitigating state-related issues). However, again, this may not affect your particular program / offer at UCSD, and especially as I would believe molecular and cell biology is one of UCSD’s premier programs. Yet it does not hurt to take these budget issues into consideration; the best example I can give is a faculty member at UC-Berkeley, whom I went to grad school with (at a private institution), had her telephone (!)-- along with the phones of the entire department – removed from her office a few years due to budgetary austerity measures. Of course, your mileage may vary, but better to know possible ripple effects now, now rather than several years into a program.
Best of luck in your PhD!