Read about KDC Partnership, which was a joint venture between Komatsu of Japan and Dressner of US. I think Harvard Business Review did a case on this as well. This 5 year joint venture shows how stereotypes/assumptions/cultural differences can lead to major issues and unless addressed there are serious implications. In KDC partnership they did addressed the issues and both companies succeeded and achieving their goals. Another good case to observe is Philips-Whirlpool case which was between a US firm and a European firm which also ended well.
Big deals might be signed at the top but they are executed on the bottom and unless one educates himself in cultural differences and acts towards good faith, the results can be disastrous for both individual and the company