Thyroid tumor bulk contains stem-like cells. (A) Percentage of ALDHhigh cells within K1 and BCPAP cell lines: 23.6% in K1, 4.87% in BCPAP. (B) Immunofluorescence anatlysis of SOX2, OCT3, BETA-CATENIN, and TSHR on primary cell cultures (zoom 40×; confocal microscope). (C) Optimization of isolation methods. Cell culture maintained in attachment and ultra-low adhesion, in the presence or absence of FBS (magnitude 10×; optical microscope).