In my previous lab it was just in water (for cell culture assays to induce gene expression by LPA treatment). Don't know if it's the best for your tasks.

Sigma states the following (http://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma/Product_Information_Sheet/2/l7260pis.pdf):

"Analytical evaluation at 10 mg per ml of chloroform:methanol:acetic acid (95:5:5) gives a clear solution. Solubility in dimethylsulfoxide (DMSO) or ethanol is limited. The sodium salt of oleoyl-LPA is reported to be readily soluble at 5 mg per ml (approx. 11 mM) in calcium and magnesium free buffers. Solution has also been achieved in phosphate buffered saline (PBS), pH 7.2, at up to 0.3 mM (0.14 mg per ml) in the

presence of 0.1% (w/v) bovine serum albumin (essentially fatty acid free)."