Hhat depletion reduces proliferation of ER positive breast cancer cells. A, Hhat mRNA expression in indicated breast cancer cell lines and a control cervical cancer (HeLa) cell line, was measured by qRT-PCR. Hhat expression is shown relative to the expression in HeLa cells, which is set to 1. Bars represent mean ± SD (n = 3). Experiments were performed twice in triplicate. B-J, Total cell number at day 6 for (B) T47D, (C) MCF7, (D) HCC1428, (E) CAMA-1, (F) BT474, (G) TamR, (H) MDA-MB-231, (I) BT549, and (J) Hs578t. Cells stably expressing scrambled or Hhat shRNAs were seeded at 5-7 × 104 cells/well, depending on cell type, in 6-well plates and cell numbers were quantified on day 6. For panels B-J, Bars represent mean ± SD (n = 3). Three independent experiments were performed in duplicate using cells at three different passages. *P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001; ****P ≤ 0.0001; Student’s t test.