D SHP1IP in the presence and absence of SHP1 tail phosphorylation. SHP1 was immunoprecipitated from J.CaM1.6LCK‐Tet cells. Where indicated, LCK expression was induced with doxycycline prior to the experiment or Src‐kinase inhibitor PP2 was used to abolish residual SHP1‐pY564. The upper panel of immunoblots shows the effect of LCK activity on SHP1‐pY564 levels. The red arrowhead indicates residual pY564. Isolated protein complexes are shown in the lower panels. 