Possible Clues:

• Dr. who turned 40 in 2005
• G-funk's Dr. ---
• Hip-hop doc?
• Beats by ___ (headphones)
• Rapper Dr. --
• Cube's former groupmate
• 'Dr.' of rap music
• Dr. certified by the RIAA
• Dr. __ (rap artist)
• 'Forgot About ___' (2000 Grammy-winning rap)