Effect of genomic DNA contamination in total RNA. (A) 1% agarose gel of purified MCF-7 total RNA samples. L-1 kb ladder (Invitrogen); Col. – column purified RNA; D20 – DNase treated/PCI extracted (RNA concentration – 20 μg/100 μl); D5 – DNase treated/PCI extracted (RNA concentration – 5 μg/100 μl); LiCl – DNase treated/Lithium Chloride purified. (B) Agilent Bioanalyzer image of MCF-7 total RNA sample purified using column method. Arrow pointing at shoulder after 28S band indicating genomic DNA carry over. (C) 1% agarose/formamide denaturing gel of MCF-7 aRNA. L1 – 6000 RNA ladder (Ambion); L2-1 Kb ladder (Invitrogen). (D) Absorption at 260 nm of nucleic acid products derived from the 4 total RNA purification methods. 2 μg of total RNA from each of the five cell lines was amplified with and without reverse transcriptase being added to the cDNA synthesis reaction (with RT and no RT respectively). C – column; Li – LiCl precipitation; D5/D20 – as in A. Cell lines included MCF-7, ZR-75-1-1, OCUB-M, Cal51, and HCT-1187.