1) Transfer to a 24 wells plate the desired colonies. 2) Once the cells are attached (at least 8 hours after tripsinizing them) add ~1 ml of DME (met-, cys-). 3) Add 3l of Met 35S, Cys 35S trans label. 4) Incubate at least 5 hours at 370C (Put plate(s) inside a tupperware, containing a beaker with activated charcoal, and close loosely). 5) Collect the media into 1.7 mL tubes and add 5l of the desired antibody. 6) Incubate at least 1 hour using the mixer located at cold room. 7) Centrifuge briefly. 8) Add 100l of a 75:25 protein A:50mM Tris mixture. 9) Incubate at least 1 hour using the mixer located at cold room. 10) Centrifuge briefly. 11) Remove the supernatant using a 5 ml syringe with a 26 1/2 G needle. 12) Add 1 mL of 1 x PBS/0.05% Tween to the beads. 13) Mix by tapping and by inverting it a couple of times. 14) Centrifuge for 30 seconds at 6,000 RPM. 15) Repeat steps 12-14 two more times. 16) Repeat steps 12-14 one more time but instead of adding 1 x PBS/0.05% Tween add 1 x PBS. 17) Take as much volume as you can out of the beads and add 10l of 50 mM tris and 15l of non-denaturing loading buffer. 18) Boil samples at least 5 minutes. 19) Load as much as you can on an SDS-PAGE (I use 15% Gels) gel. 20) After running the gel incubate it 45 minutes on 30% ETOH:10% HOac. 21) Dry gel for 1.5-2.0 hours at 70 C. 22) Expose O/n to a phosphoimager screen.