PLEKHF1 , POP4 and TSHZ3 expression is selectively required for the survival of 19q12-amplified breast cancer cells. (A) Barplots illustrating the survival fractions of cancer cells with (red) or without (black) 19q12 amplification upon transfection with short interfering RNA (siRNA) targeting POP4, PLEKHF1, UQCRFS1, CCNE1, ZNF536, and TSHZ3 relative to siRNA controls (siCON) of individual duplex oligonucleotides (1 to 4). Error bars represent the standard error of the mean of three replicates. Reduced cell viability effects were considered validated if at least two individual oligonucleotides caused a significantly higher loss of viability of cancer cells harbouring 19q12 amplification than in those lacking amplification of this locus (* depicts significant t-test P-values for the comparison of the survival fraction between cells with and without amplification of the target gene for an individual oligonucleotide). siZNF536 failed to validate with two or more individual siRNA oligonucleotides. (B) Effects on target mRNA expression after silencing of PLEKHF1, POP4, TSHZ3 and CCNE1 with individual oligonucelotides in MDA-MB-157 cells as determined by quantitative RT-PCR. (C) Effects on target protein expression after silencing of PLEKHF1, POP4, TSHZ3 and CCNE1 with Dharmacon individual oligonucelotides and smartpool (SP) in MDA-MB-157 (CCNE1) and MCF7 cells (PLEKHF1, POP4, and TSHZ3) as determined by Western blotting.