Fig. 7. Effects of NH2-terminal deletions on the subcellular distribution of p94fer. A, fer1376 (a), fer1328 (b), fer1299 (c), fer330376 (d), fer1147 (e), and fer 1178 (f) were transiently expressed in actively growing COS1 cells. Cells were fixed and stained with -HA monoclonal antibody. Scale bar, 20 µm. B, schematic summary of the p94fer (fer) deletions which were tested in these experiments. Signs describing the nuclear accumulation of the different constructs are as in Fig. 3B , and the values were determined according to the described procedure. C, a schematic description of the key functional and regulatory elements in p94fer. C, CC-forming regions; SL, the small lobe of the kinase domain; LL, large lobe of the kinase domain; NLS, nuclear localization sequence. The NH2-terminal elements that modulate the NLS activity are shown. The linker between CC regions I and II (negative effect) cooperates with CC regions II and III (positive effect) to impose cell cycle regulation on the FER NLS (for more details, see text).