Luke 9:23; Matthew 10:38, but I'm sure there are other verses in the Gospels and in Paul's writings that deal with what the symbol of the cross means. I know the cross is central in the New Testament. The cross as a symbol of discipleship (Matthew 16:24), etc.
Luke 9:23
ESV - 23 And he said to all, "If anyone would come after me, let him deny himself and take up his cross daily and follow me.
For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.