In Early Vertebrate Embryonic Development, a Number of Pathways, Such

Multiple Choice

In early vertebrate embryonic development, a number of pathways, such as Wnt, Hedgehog, and Notch, regulate differentiation and organ formation. They operate by __________.

A) formation of new transcription factors at each stage
B) transcription activation due to interaction among transcription factors
C) cell signaling mediated by receptor binding
D) establishing anterior-posterior and dorsal-ventral symmetry
E) stimulating MADS box genes