d X is H. [0141] Other suitable Hydroxyureas are disclosed in, e.g., U.S. Pat. No. 5,066,658, wherein R2 and R3 together with the adjacent nitrogen form: [0142] wherein m is 1 or 2, n is 0-2 and Y is an alkyl group. [0143] In one aspect, the hydroxy urea has the structure: [0144] Hydroxyureas are thought to function as Cell Cycle Inhibitors by serving to inhibit DNA synthesis. [0145] In another as