In endogenous producers (HT1080/C1 fibrosarcoma transfectants with doxycycline (dox) regulated shHMGA2 expression and RD rhabdomyosarcoma cells) and the HMGA2 transfectants of undifferentiated thyroid carcinoma cells UTC8505, HMGA2 was exclusively detected in nuclear protein extracts. This evidence concerns the gene HMGA2 and thyroid gland undifferentiated (anaplastic) carcinoma.