Practice question

Tertiary vulval precursor cells must avoid responding to low LIN-3 despite molecular competence maintained by LIN-39. LIN-12 Notch activity in P3.p, P4.p, P8.p and induced cells modulates EGFR sensitivity by cross-inhibition. LIN-12 signaling upregulates LIP-1 dual-specificity MAPK phosphatase, LST-1-4 inhibitors, DPY-23 adaptin dampening LET-23/MAPK cascade and Ras output. Additionally, LIN-12 promotes expression of synMuv B genes including lin-35 retinoblastoma antagonizing EGF induction via chromatin remodeling. This reciprocal inhibition between RTK and Notch ensures only P6.p attains high MAPK, distal VPCs remain hypodermal despite low LIN-3.