(A) Western blots for tau (45–75kDa) revealed an increasing expression and molecular weight range as tumorigenicity increases from the HMEC cells to HCC1428. β-actin served as loading control. (B) McTN frequency increases concomitantly with tau expression. HCC1428 forms significantly more McTNs than lower tau expressing cells lines. ZR-75-1 forms significantly more McTNs than, HMEC, 184A1, 184B5, MCF-10A and Sk-Br-3. Data (n=3) are represented as the mean ± s.d. *P<0.05. (C) ZR-75-1 and HCC1428 were subjected to indirect IF for tau followed by direct IF for α-tubulin. As tau expression increases, localization of tau within McTNs increases (white arrows). Cells and McTNs displayed are representative of those under conditions of actin depolymerization.