To test the hypothesis that PFKFB3 and PFK1 expression is regulated in a cell cycle-dependent manner, the level of PFKFB3 protein was analyzed in breast cancer cells (SKBR 3, MDAMB 468, BT 474) synchronized using a double thymidine block (DTB) and/or nocodazole treatment. Here, PFKM is linked to breast carcinoma.