Out of 4 core Ps of Marketing i.e. Product, Price, Promotion and Place, which one is the most important?

I guess PRODUCT is the most important part of Marketing Mix. As Sir IRPHAN GHANI said above that if there is no product then the question of Price, Promotion and place.

All are important in marketing and are inter dependent; however if there is no product then the question of price, promotion and place would not arise.

Product is the key, without product there would be no marketing. But Product in today's scenario depends on Promotion because without promotion strategy nothing reaches to the end customer. Social Networking is a vital in modern day enhancement so Promotion is required for everythihng be it a small product to even releasing a movie it requires a Promotion.

Product is important (as to its' quality and alternatives) followed by price, place and promotions.  The better the composition, the better the Marketing strategy.

yes product is the most important, you can do a bad job in pricing, promotion, placing, but still you get some one to buy the product.