By way of some information on SOPs (to stop some of the misinformation on this thread so far):
1) TCAS and GPWS warnings take priority over ATC considerations - remember that the Russian airliner involved in the DHL midair followed ATC instructions instead of TCAS.
2) GPWS warnings are to be followed in all instances except when in day VMC - in this instance (only) a GPWS warning does not need to be followed if a visual terrain assessment confirms that there is no danger to the aircraft.