Expressed KSHV TK colocalizes with a protein(s) stained by an anti-pTyr antibody. (a) 143B TK- cells expressing EGFP-KSHV TK (panels 1 and 5) were costained for tyrosine phosphorylation (anti-pTyr) (panels 2 and 6), and the images were merged (yellow) (panels 3 and 7). (b) 143B TK- cells expressing EGFP (panel 1), EGFP-HSV1 TK (panel 4), EGFP-KSHV TKΔATP (panel 7), or mock transfected were costained with anti-pTyr as shown in panels 2, 5, 8, and 10, respectively. Cells counterstained with Hoechst are shown in panels 4 and 8 (a) and panels 3, 6, 9, and 11 (b) (blue staining).