Effect of ?-irradiation and IFN- on IP6K2 protein levels. (a) NIH-OVCAR-3 cells growing at 75% confluence were trypsinized, suspended in 1 ml PBS, and subject to 0, 1 (white bars) or Gy (gray bars) irradiation and replated in complete medium. At 8 and 16 h after plating, cells were harvested, lysed and subject to Western blot analysis using monoclonal anti-IP6K2 antibodies. To control for loading, blots were probed with anti-actin antibodies; bands were digitized and quantified. IP6K2 signal intensity was normalized to actin, then expressed as fold induction, with unirradiated cells representing a protein level of 1. Purified rIP6K2 was included as a positive control (lane 1). Numbers to right of blots indicate MW markers. Only relevant portion of the blots are shown. (b) NIH-OVCAR-3 cells were grown in the presence of 200 U/ml IFN- for 0-48 h and then subject to Western blot analysis and quantified as above.