GLS and breast carcinoma: Our previous studies indicated that GAC activity might be regulated by phosphorylation in breast cancer cells.12 To investigate whether a similar molecular mechanism is responsible for the elevated GAC activity in NSCLC cells, we expressed V5-GAC in H1299 cells and immunoprecipitated GAC using an anti-V5 antibody to determine the effects of alkaline phosphatase treatment on glutaminase activity.