PP1 prevented the growth of two human papillary thyroid carcinoma cell lines that carry spontaneous RET/PTC1 rearrangements and blocked anchorage-independent growth and tumorigenicity in nude mice of NIH3T3 fibroblasts expressing the RET/PTC3 oncogene.     ///    "Furthermore, RET/PTC3-transformed cells treated with 5 microM of PP1 lost proliferative autonomy and showed morphological reversion. "