Dollar General, Rue21 today. Toys 'R' Us next?Toys "R" Us may be one of the next private-equity backed retailers to sport an initial public offering, says retail consultant Howard Davidowitz, founder of Davidowitz & Associates. The toy store chain would follow on the heels of successful public debuts Friday of discount retailer Dollar General Corp. (NYSE:DG), backed by Kohlberg Kravis Roberts & Co., and teen apparel retailer Rue21 Inc. (NASDAQ:RUE), backed by Apax Partners Worldwide LLP. Last month, Vitamin Shoppe Inc. (NYSE:VSI), backed by Irvingplace Capital Management LP and Blackstone Group LP (NYSE:BX), became the first U.S. retailer to go public in two years. . Also in October, Dollarama Inc., backed by Bain Capital LLC, debuted on the Toronto Stock Exchange. Private equity firms in general and KKR in particular are expected to take more of their portfolio companies public soon. The Deal spoke with Davidowitz Friday on the floor of the New York Stock Exchange, as part of our on-going video series about IPOs, shot on location there. -- Mary ...