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. Author manuscript; available in PMC: 2015 Sep 1.
Published in final edited form as: Mol Cancer Res. 2014 Jun 19;12(9):1334–1343. doi: 10.1158/1541-7786.MCR-14-0049

Figure 1.

Figure 1

Figure 1

Figure 1

Id1 but not Id2 promotes metastasis. (A) Cell growth of MDA-MB-436 cells expressing Id1 shRNAs. Down-regulation of Id1 expression in MDA-MB-436 cells did not affect cell growth. (B–D) Down-regulation of Id1 expression decreased cell migration, invasion and metastasis. MDA-MB-436 cells stably expressing a control shRNA or Id1 shRNA were subjected to migration assay (B) and invasion assay (C). Knockdown of Id1 expression in MDA-MB-436 cells suppressed cell migration and invasion. (D) Transplantation of luciferase-tagged MDA-MB-436 cells stably expressing a control shRNA via tail vein injection led to metastasis (8 out of 10 mice developed lung metastasis), whereas transplantation of MDA-MB-436 cells stably expressing Id1 shRNAs did not (only 1 out of 5 mice in each of the Id1 shRNA group developed metastasis) (Fisher’s exact test p=0.023). Knockdown of Id1 expression in MDA-MB-436 cells suppressed metastasis. (E) Tumor growth in the primary site after the transplantation of human breast cancer MCF7 cells stably expressing Id1 or Id2. There is no significant difference between two groups. (F) Transplantation of MCF7 cells stably expressing Id1 in mammary fat pads leads to metastasis (10 out of 10 mice developed lung metastasis), whereas transplantation of MCF7 cells stably expressing Id2 does not (only 1 out of 10 mice developed lung metastasis) (Fisher’s exact test p<0.001).