Indicate whether each of the following descriptions better applies to mitogens (M), growth factors (G), or survival factors (S). Your answer would be a four-letter string composed of letters M, G, or S only, e.g. GMSG. ( ) They unblock cell-cycle progression ( ) They suppress apoptosis ( ) They trigger a wave of G1/S-Cdk activity ( ) They inhibit the degradation of cellular macromolecules