1 EXHIBIT 23.1 CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS To Cell Pathways, Inc.: As independent public accountants, we hereby consent to the incorporation by reference in this registration statement of our report dated February 4, 2000 included in Cell Pathways, Inc.'s Form 10-K for the year ended December 31, 1999 and to all references to our Firm included in this registration statement. /s/ ARTHUR ANDERSEN LLP Philadelphia, Pennsylvania November 22, 2000 II-6