I did a search on SciGine and found that the Life Technologies manufacturer protocol seems to be quite accurate. Here are 2 methods. One of which you should look at the original paper and follow the manufacturer's instructions. And in the second is a method based around PEI for transfection of SAOS-2 cells. 

http://scigine.com/method.php?ID=52208

http://scigine.com/method.php?ID=272048

Hello

look at thes  protocol by John Fuesler and et al " Saos-2 cells (4.5×105) were seeded in 60 mm cell culture dishes in 2 ml antibiotic-free D-MEM. Next 200 µl serum-free and antibiotic-free D-MEM, 2 µl of p53-containing PAC DNA (1 µg/µl) and 12 µl PEI (1 mg/ml solution) per dish were added to sterile polypropylene tubes, vortexed briefly and incubated at room temperature for 15 min. Aliquots of the DNA:PEI complexes were pipetted into media of culture dishes. Dishes were then incubated as described above in the absence of any selection, and the transfection media was replaced with complete media 12 h post-transfection. For Lipofectamine 2000 transfections used only in the Annexin V-FITC apoptotic assays, 5×104 Saos-2 cells were seeded in 500 µl antibiotic-free D-MEM per well of a 24-well plate. Transfections were performed in accordance with the manufacturer's specifications by complexing 0.8 µl of the Lipofectamine 2000 reagent with 0.8 µg DNA per well. Transfection media was replaced with antibiotic-free D-MEM 4 h post-transfection" .

http://web.mit.edu/beh.109/www/lipo.pdf

http://jeccr.biomedcentral.com/articles/10.1186/1756-9966-33-19

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3488463/

Thank you for your replies :)