EXHIBIT 99.1

                            EXPLANATION OF RESPONSES
                            ------------------------

(1)  The stockholders are Warburg, Pincus Ventures, L.P., a Delaware limited
     partnership ("WPV"), and Warburg Pincus & Co., a New York general
     partnership ("WP"). The sole general partner of WPV is Warburg Pincus
     Partners LLC, a New York limited liability company ("WPP"), whose managing
     member is WP. Warburg Pincus LLC, a New York limited liability company ("WP
     LLC" and together with WPV, WPP and WP, the "Warburg Pincus Entities"),
     manages WPV. Charles R. Kaye and Joseph P. Landy are Managing General
     Partners of WP and Managing Members of WP LLC and may be deemed to control
     the Warburg Pincus Entities. Messrs. Kaye and Landy disclaim beneficial
     ownership of all shares held by the Warburg Pincus Entities. Kewsong Lee, a
     director of Knoll, Inc., is a general partner of WP and a managing director
     and member of WP LLC. All shares indicated as owned by Mr. Lee are included
     because of his affiliation with the Warburg Pincus Entities. By reason of
     such affiliation, Mr. Lee may be deemed to have an indirect pecuniary
     interest within the meaning of Rule 16a-1 of the Securities Exchange Act of
     1934, as amended (the "Exchange Act"), in an indeterminate portion of the
     shares reported herein. Mr. Lee disclaims "beneficial ownership" of such
     shares within the meaning of Rule 13d-3 under the Exchange Act.