Combination of antibiotics 10,000 I.U. Penicillin (per mL) 10,000 µg/mL Streptomycin 25 µg/mL Amphotericin with 8.5 g/L NaCI can be used . It is available commercially.
Beside Pen/Strep, you can also find antibiotics for selection of cells expressing antibiotic resistant genes such as: puromycin, gentamycin (G418), blasticidin. All are commercially available.