Cell growth as monitored by 31P MRS. The 1H-decoupled spectra of DMMP seen on the left were obtained immediately following the acquisition of the 31P NMR spectra shown on the right. DMMP, dimethylmethylphosphonate; GPC, glycerophosphorylcholine; NTP, nucleoside triphosphates; Pi, inorganic phosphate; PME, phosphomonoesters.