Satisfactory identification of the neoplastic cell as well as an optimal G-banding of its chromosomes are routinely obtained in our laboratory using a modification of the method described by Knuutila et al. Mitotic cells are first identified by either cytochemical or immunological staining. For G-banding, the preparations are then destained with methanol:acetic acid, treated with 2 x SSC at 65 degrees C and restained with Wright stain.