Reexpression of LAT or Syk restores calcium mobilization in RNKDLS. RNKDLS cells were infected with control Vaccinia virus (pSC65) or recombinant virus expressing LAT or Syk, as indicated. (A) Aliquots of cells were removed for immunoblotting with LAT and actin, and (B) remaining cells were loaded with calcium-sensitive dyes and assayed for calcium mobilization after treatment with anti-Ly49D (4E5) and crosslinker. (C) In a second experiment, RNKDLS cells were infected as indicated. Similar to panel A, postnuclear cell lysates were immunoblotted for Syk or PLCγ1 as indicated and (D) remaining cells were assayed for calcium mobilization as in panel B. Max% indicates maximum percentage of cells responding.