Fig. 4. KIS-L is associated with regions of active transcription. (A-C) KIS-L (red) and Pol II (green) were detected on wild-type polytene chromosomes using antibodies against KIS-L and the 140 kDa subunit of Pol II (Pol IIc); the merged image is shown in C. (D-G) Magnifications of the distal regions of the X chromosome and chromosome arm 3L (white rectangle in C) are shown. The distributions of KIS-L and Pol II are highly overlapping, although the levels vary from site to site, as evident in the split image (G).